HISTORICAL NOTES ON THE USE OF AIR POWER AS A WEAPON OF INTERDICTION

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78T02095R000800070002-2
• Release Decision: RIFPUB
• Original Classification: S
• Document Page Count: 40
• Document Creation Date: December 20, 2016
• Document Release Date: January 23, 2006
• Sequence Number: 2
• Publication Date: May 1, 1966
• Content Type: REPORT

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SECRET
CIA/RR ER 66-8
May 1966
INTELLIGENCE REPORT
HISTORICAL NOTES ON THE USE OF AIR
POWER AS A WEAPON OF INTERDICTION
USAF review(s) completed.
DIRECTORATE OF INTELLIGENCE
SECRET
GROUP 1
Excluded from automatic
downgrading and
declassification
MORI/CDF
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i''iis ntatt rral c)ntains inns rmation ,.Hecting t ? i la-
tional l)efenst of the Unitt d States within the ne tn-
in,g of the espionage laws, Title 18. USC, Sec ' 93
timi 794, the transmission or revelation of wl. ch in
;my urunur an unauthorized heron is prom ihi ed
l,; law.
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FOREWORD
Prior to the current operations in Vietnam, the United States was
engaged in three wars in which air power played a major role as a
means of conducting offensive warfare. This report summarizes the
role of air power in the air wars against Germany, Japan, and North
Korea. The analysis of the air wars against Germany and Japan
treats in general terms the overall economic effects of the campaign,
with somewhat more detailed treatment of the attacks on transporta-
tion. The air war against Korea is most similar to the air war being
conducted in North Vietnam. For this reason the Korean War is
examined in greater detail to evaluate the attempts to interdict North
Korea's transport system.
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CONTENTS
Page
1. The Air War Against Germany .... .. ... 1
A. The German Economy . ...... .......... 1
B. Overall Economic Effects of Bombing .. ... ... 2
C. Target Systems . ... .......................... 3
1. Civilian Morale . ............... ......... ..... 4
2. The Attack on the Ball-Bearing Industry .... .. .... 5
3. The Aircraft Plants as a Target System . ... ... ... 5
4. The Attack on the Petroleum Industry ..... ....... 6
D. The Attack on Transportation .......... .. .. ... 7
1. Inland Waterways 8
2. Railroads 8
II. The Air War Against Japan 11
A. The Air Attacks Against Japan Proper 11
B. Effects of the Attacks .. .... .. ...... ... ... .. . 12
C. Civilian Morale .............. ........... .. . 12
D. Destruction of Japanese Merchant Shipping .... . .. . 13
E. Actions of the Elite to End the War .............. ... 15
III. The Air War Against North Korea . .. ... ..... ....... 17
A. Introduction ....................... ........... . 17
B. Similarities and Differences of Environment 17
C. Interdiction in North Korea 17
1. Introduction ................................... 17
2. Railroad Interdiction-Operation Strangle ..... .. 21
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Page
I. :valuation oI Operation S:_rangle 23
aa. Introduction 23
h. Railroad Interdiction 24
C. Highway interdiction 24
d. Night Operations 25
The 'A,'a-dorag Chokepo]nt 26
D. Strategic Bombing 27
Early Bombing 27
2. 1,ater Strategic bombing Efforts 29
a. hydroelectric Power 29
la. I rr: gation. Dam:; 29
F- i xessons from the Korean War 3t)
Introduction 30
Failure oil the fn:erdiction Campaign 30
3 . Air Pressure l ac:ics and Psychological V6'-Mare 32
=-9:. Lessons for Vietnam 33
1. Distribution of Bomb [onager n the Europe !n. Theater
Du firing World War tI 3
2. Comoari.son of Air Oner;.tions in Korea ar d Nortl % ietnani 19
3. Strategic Targets Attacked in North Korea, 1950 28
C HARS
?: ollows Fage
Figure I. Effect of Allied Bombing cm German Mui.itions Pro-
duction 33
Figure 2. Effect of Allied Bombing oa japarese Muuit.ens Pro-
duction anca Maritime Saipnink; 33
f{'figure 3. Indexes of Berrrl;s Expended and Value f i estruc-
tion in the Korean War During Opeerati ~ yr, Strangle 33
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HISTORICAL NOTES ON THE USE OF AIR POWER
AS A WEAPON OF INTERDICTION*
1. The Air War Against Germany
A. THE GERMAN ECONOMY
The German war economy benefited greatly from the German
buildup in industrial activity which took place between 1933 and
1939. While both England and the United States entered World
War II with substantial unemployment, the German labor force was
fully employed by 1939. Six years of rising output (1934-39) meant
that substantial investments were made in expanding plant facilities,
both for heavy industry and for armament production. One result
was that the German armament industry, with few exceptions, worked
only single shifts throughout the war and the great reserve capacity
available from double or triple shift operations not only gave con-
siderable flexibility but also cushioned the effects of Allied air attacks.
In 1.938, approximately 30 percent of the national product was already
devoted to war expenditures, and this level rose very slowly until,
by the end of 1944, approximately 50 percent of the national product
was channeled into war purposes.
The output of civilian consumption goods, after the restrictions in
the initial war years, was reasonably well maintained so that civilian
standards of living continued to be, comfortably above the levels of
the depression years of the early 1930's.
Germany's dependence on imported raw materials was always looked
upon as a classical weakness in wartime. The four-year plan of
1936 was aimed in part at overcoming the most serious of these weak-
nesses, chiefly through expanded production of synthetic oil, textiles,
and rubber. However, Germany imported very substantial percent-
ages of iron ore, copper, manganese, and other metals. Partly as a
result of overrunning other Western European sources of supply and
* This report was prepared by the Office of Research and Reports; the estimates and
conclusions represent the best judgment of the Directorate of Intelligence as of 15 April 1966.
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partly as a result of substitution, Germany managed until well into
1.944 to avoid se:' ious embarrassment from s nortage,l o' imported war
Material. The Germans found that consumption o'? r mny materials,
such as copper, traditionally believed to be essential to armaments
production, could be drastically cut without materially affecting the
iuality or the usefulness of the end product.
While electric power supplies became tight eariv n the war, ra-
tioning and curtailment of nonessential use! permitt:ec. priority needs
to be met until 1944. During that year, certain r major industrial
consumers., such as aluminum producers, were depri red of supplies
from time to time on a. temporary basis.
In summary, the German economy proved sum p1isiingly able to
withstand substantial attac.Ks and still increase mun lions output until
the weight of Allied bombardment increases. to apps ox imately 300,000
tons a quarter, which did not take place until fate in 1944 (see
Figure 1).
8, OVERALL ECONOMIC EFFECTS OF BOMEING
During 1942 ,and 1943 the overall effects of air ra.=d! on the German
economy were small. The LUS Strategic 1,ombing S zrvey estimated
that the total loss of German armament oroduct:o;on resulting From
air attacks carried out in 1943 was not more than 3 to 5 percent, even
though the attacks requirec the Germans -:o call upc n. some of their
reserves.
In the first four months of 1944 the US air forces ccn.centrated their
effort on aircraft plants and on antifriction lreari,ug factories. The
vulnerability of these targets provec: smaller than has. been expected.
In May and June of 1944 the weight of attacks oi Germany was
reduced because of the diversion of a high props rti on of the Allied
air forces to preparation for the invasion that was lauwrched on 6 June.
The air offensive that started later, beginning vwit]i attacks on oil
and nitrogen facilities a.nc. continuing against German transportation,
achieved more noticeable results. . Before the end of 1944 the output
of aviation gasoline and nitrogen had fallen by 9) percent. The
attack on transportation was a major factor in reducing the volume
Of car loadings by `75 percent within five months. i1c wever, the index
of armament production stayed high. It reached a 3eak in the third
quarter of 1944; the decline in the fourth quarter (t -o:m causes other
than those attributable to territorial losses was oily about 5 percent.
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The Allied bombing program did succeed in tieing up a significant
portion of the labor force by the third quarter of 1944. An estimated
41/2million workers, or nearly 20 percent of the nonagricultural labor
force, were engaged in debris clearance, reconstruction and dispersal
projects, the replacement of goods lost through air raids, and in the
manning and production of antiaircraft munitions. Air raid casualties
reduced the labor force by no more than 500,000 to 700,000, or about
2 percent.
From December 1944 onward, all sections of the German economy
were in a rapid decline. This was due to the results of bombing
in combination with other causes, particularly the military reverses
which had led to the invasion of Germany itself. In February 1945,
Silesia and the Saar had been lost, and car loadings were only 11 per-
cent of normal and still falling. The final land actions carrying the
Allied armies across the Rhine and Oder Rivers were under way by
the time the economy of Germany had ceased to be able to support
significant military operations.
C. TARGET SYSTEMS
The greatest weight of Allied air attack, approximately 56 percent,
was delivered against two target systems-land transportation and in-
dustrial areas (see Table 1). Transportation targets are discussed in
D, below.
The attacks against industrial areas, generally identified as city area
raids, were primarily the work of the Royal Air Force. It began its
famous raids on German urban areas in 1942, with the first thousand-
plane raid against Cologne. This was followed by heavy attacks on
other industrial cities, the most noteworthy of which were the July
Distribution of Bomb Tonnages in the European Theater
During World War II
PERCENT
Land transportation targets ....... ............................. ..... 32.1
Industrial areas ..................................................... 23.7
Military targets ................................................... 11.1
Oil, chemical, and rubber targets ...................................... 9.3
Airfields and airdromes ............................... ............ 6.9
Naval and water transportation targets ................................. 4.2
V-weapon launching sites ............................................. 2.0
Aircraft factories ........................................ .......... 1.8
Miscellaneous manufacturing targets ................................. 2.6
All other targets .................................................... 6.3
Total ....................................................... 100.0
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and August strikes against Hamburg. Th,,, Hamb.ir,- raid destroyed
about one-third. of the residential housing and kills=d between 60,000
and 100,000 people. While this raid had in immt-diite shock effect,
the city attacks prior to the autumn of 1944 did not ;u )stantially effect
German war production. Recovery was E ssentialiv achieved within
a relatively few weeks, and because industrial plants were generally
located around the perimeter of German cit:les, ht v were chr.rac-
teristically undamaged.
The heavy tonnages of bombs dr-)pped on -.rrban . trews as a result
of attacks on transportation and targets beginning in September 1944
,produced more significant effects. However, since there were so
roany forces contributing to the collapse of produc ric n in the last six
months of the war, it has not been possible to as-esi separately the
effect of these later area raids on war pr eduction..
1. Civilian Morale
The conclusions of the US Strategic Boribing Si.r,,ev with respect
i:o the effect of Allied air attacks on Germar morale are as follows:
'ftc Survey has made extensive studies of the rea ti( n of German
people to the air attack and especially to city -aide. Ti-,es studies were
carefully designed to cov_-r a complete cross section o' the German
people in western and southern Germany and to reflect wi It a minimum
of bias their attitude and behavior during he raids These studies
show that the morale of the German people deteriorn'ec under aerial
attack. The night raids were feared far more than dau:ig It: raids. The
people 'lost faith in the prospect of v ctory, in their le ,dt ra and in the
promises and propaganda to which trey wer,. subject, d. Most of all,
they wanted the war to ens. They resorted inccreasingh, tc "black radio"
listening, to circulation of rumor and fact in oppositior t' the Regime.
and there was some increase in active political dissider e---in 1944 one
German in every thousand was arrested for a political otF Anse. If they
had been at liberty to vote themselves out of -he war. lie / wouH have
]on.: so we'll before the finoil surrender. In ~ determ:,~ei police state.
however, there is a wide difference between dissatisfacti, ~n tnd expressed
opposition. Although examination of official records n( those of in-
dividual plants shows that absenteeism increased and or rductivity di-
minished somewhat in the late stages of the war, by a:.d arge workers
continued to work. However dissatisfied the- were w -th the war, the
German people lacked either the will or the means to mike their dis-
satisfaction evident.
The city area raids have left their mark on tl-e ( n an pecple as
well as on their cities. Far more than any other milrar v action that
preceded the actual occupction of Germany it;elf, these a tacks left the
German people with a solid lesson in tae disadvantages ~t Nar. It was
_; terrible lesson.
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2. The Attack on the Ball-Bearing Industry
The classic example of an attack on a so-called bottleneck industry
was that of the German hall-bearing industry. Not only was ball-
bearing production concentrated, with approximately one-half of the
output coming from plants in the Schweinfurt area, but also Germany
was assumed to need a continuing full supply of ball bearings to
continue war production.
Air attacks on Schweinfurt took place on 17 August and 14 October
1943. Losses to attacking German fighters (the plants were outside
of escort range) were such that the attacks could not be maintained.
During the next four months, when there was a bombing lull, the
Germans took energetic steps to disperse the industry. This dispersal
was aided by the fact that machine tools were relatively undamaged.
Furthermore, it proved possible to eliminate very high percentages
of the total number of ball bearings used in some equipment without
materially impairing its operation for either civilian or military pur-
poses. The Germans had also exercised the precaution of accumu-
lating substantial stocks. From examination of the records in the
ball-bearing industry, and from the testimony of war production
officials, there is no evidence that the attacks on the ball-bearing
industry had any measurable effect on essential war production.
3. The Aircraft Plants as a Target System
The abortive experience with the ball-bearing industry was followed
by renewed attacks on the German aircraft industry. Earlier attacks
had the effect of reducing the vulnerability of aircraft assembly plants
because the Germans pursued a policy of subdividing and dispersing
aircraft production facilities. The new attacks began in February
1944, with the protection of long-range fighter escorts, and were
again aimed at aircraft assembly plants as opposed to aircraft engine
plants. These attacks did not succeed in reducing the production of
aircraft, probably because there was considerable excess capacity in
the assembly phase of the aircraft industry and because, once again,
relatively simple protective measures prevented serious loss of machine
tools. Hence the attack on the ball-bearing industry and the attack
on aircraft assembly facilities were proved to be errors in target se-
lection. The German Air Force was defeated, but its defeat came
largely as a result of combat operations by the Allied forces. Later
in the war the Ruhr steel industry was singled out as a target system,
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but because steel lies so deep in th,,~ indu!trial prc-~ss there is no
evidence that these attacks affected munitic ns 'rod rc :ion before the
end of the war.
4. The Attack on the Petroleum Industry
The attack on the German petroleum i:iclustry b gan in a pre-
liminarY 'way with two st_ikes in May 1144. I'll :--s ~ attacks were
not followed up, because of the almost complete c iversion Of air
power to attacking tactical targets in preparation ii and in supi?ort
01- the D-1)ay invasion.
The German oil position was tight througho,t the war,, and
production was largely concentrated in f3 synt;re ic' fuel plants.
although there were early attacks :)n the Human at petroleum in-
dustry, by August 1994 tli s source of su)ply overrun by the
T SSH_ and German dependence on the synthetic pia rte became almost
complete.
By July 1944, every major plant had been hit. After the attacks
began in May, production. which had averaged ;a .6,000 tons per
Month, fell to 17,000 tons a month in Se )tember Although there
was a modest recovery in November and )ecemh r. the post-attack
output was only a fracuoru of the pre-attack level. _nlike the ball-
bearing plants, the synth.eiic oil plants were att. cr ed again when
they were brought back into operation. For ex_a rr.ppe, the largest
plant, Leuna, was attacked 22 times by early Nr5 and its output
from the day of the first attack ave?aged only 9 p,~nent of capacity.
The effects of depriving German, of its major r ie resources were
almost immediate in tenris of military opt rations. t or lack of fuel,
pilot training was drastically curtailed, making ( ernan aircraft in.-
creasingly vulnerable c': experienced Allied fighter As the summer
cif 1944 wore on, the German panzer divisions wrre more and more
seriously hampered by decreased tuel production. Jerman military
stocks of petroleum were so low that when the t wious Ardennes
offensive (the so-called Battle of tie Bulge) was is inched, German
reserves of fuel were insufficient to suppo:-t tree operation. The
German high command counted ur capturing Al Lei stocks to keep
the operation rolling. i':rally, in Fel)ruarv ;and vi urch of 1945 the
Germans massed 1,200 tanks on the Vistiula to Jeck the Russian
advance. In eery short order, the tanks were oti r! tuna because they
had insufficient fuel for maneuver.
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There were other dividends from the attack on the petroleum in-
dustry because 60 percent of the nitrogen and 40 percent of the
methanol output came from the synthetic oil plants. Shortages of
these essential chemicals for munitions were reflected in shortages of
ammunition within a few months.
D. THE ATTACK ON TRANSPORTATION
The German transportation system was dominated by the rail-
roads. In combination, the state-owned and privately owned rail-
roads handled three-quarters of all freight traffic and about 70 percent
of passenger traffic. Most of the remainder of the freight traffic was
accounted for by waterway (largely inland) carriers and less than
3 percent by highway vehicles. The rigid government regulation
of trucks was designed to prevent the development of a highway truck
system which would compete with the state-owned railways for long-
haul business. Therefore, motor transportation was almost entirely
limited to local and suburban service.
The rail system was well maintained and had general overcapacity
on permanent way, with respect to both lines and classification yards.
The inland waterways system connected the important rivers of North
Germany, crisscrossed the Ruhr coal area, and provided through water
transportation from the Ruhr into the Berlin area. The moderate
expansion of the rail system during the war was concentrated in those
few places where it was necessary to construct new yards in critical
points such as Munich or to parallel vulnerable viaducts with by-
pass lines.
During most of the air war against Germany the bombing of rail
transportation was not given a high priority. Although heavy major
ground operations were preceded or accompanied by concentrated
attacks on local rail facilities in or near the battle area, transportation
was not then selected as a priority target system, because of its size
and complexity. As a consequence, the railroads in Germany and
the ports of the inland waterways system were subject to only sporadic
attacks until the middle of 1944. Heavy attacks on transportation
within Germany proper did not begin until September 1944. The
recuperative powers of the system were such that until bomb tonnages
exceeded 12,000 tons per month the repair system was able to cope
with the damage.
At the same time that the heavy attacks were beginning on the
railroads, successful attacks on four waterway targets substantially
eliminated through traffic on the Rhine and North German canals.
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By 1.4 October the Rhine River was imilariv ir,terc :ctEd at Cologne,
and as a consequence the economic cratnc of the Lnportant Ruhr
district fell to about 12 percent of the leve of Oci ,h r 1943-March
19144. By he end of December., car loadings had I .-e i decreased by
about 40 percent and by 611_c first week of ,lar,rh 1 4-) by almost 80
o~ercent. The index of inhir.titiuns production heir cp substantially
aaetter than these figures would indicate, largely i et a use of stocks
Of components and suba.ssernblies.
1, inland Waterways
The general experience with the attack on wa= ei ways was that
these were relative.:ly succeessfui in smiting traffic-- o ten for a con-
siderable period of time. :,'urthermore, there were tr !(luent additive
side effects such as that resulting from the mining of -sit Danube River.
The period of intensified mine laying in Lite Danu )e was from April
to December 1944. The mines salad other aeria; a:tacks; resulted
in the sinning of over 41) percent of tale Danube can,..() sleet. Further-
in ore, t'nere was a precipitous drop in hnorale becau -e nine explosions
often resulted in the loss of the crew. Cuhisequen jv desertions and
delays because of manp(,wei shortages were thumera to. The tonnage
'handled on the river dropped about (0 percent with ii :wo months and
continued to fall throughout the sununer Conic ie :e statistics are
of available, but the 1).anube cperaticn was ciea.rly a highly
;successful one.
2. Railroads
The bomb tonnages dropped on land transpf rt.ttaon targets in
:;ermany were as follows by quarter:
1944
january-March ..
April-June ... .. ..
July-September ....
50
.,?j i0
1; `?00
October-December
'7],000
1945
January-March
Of which 13,000 tons were drooped n September.
It can be seen from the above figures that un?:i September 1944
the tonnages dropped were not sufifciew: to oy,( rwhelm the capa-
bilities of the repair system. Following t. tat date t] re weight of the
attack increased sharply and in the first quarter of 11146 was 64 times
that of the first: quarter of 1944. The result was Progressive tieup
of traffic.
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Although coal traffic (about 40 percent of all the traffic carried by
the German railroads) held up better than miscellaneous commercial
traffic, the decline was both more easily traceable and more dramatic.
The September raids reduced coal-car placements in the Essen Divi-
sion of the Reichsbahn (the originator of most of the coal traffic
of the Ruhr) to an average of 12,000 cars daily, compared with
21,400 at the beginning of the year. Most of this was for consumption
within the Ruhr. By January, placements in the Ruhr were down to
9,000 cars a day, and in February 1945 virtually complete interdiction
of the Ruhr District was achieved. The German economy was
powered by coal and, except in limited areas, the coal supply had
been eliminated.
Military (Wehrmacht) traffic had top priority over all other traffic.
During the period of attack this traffic came to account for an ever-
increasing proportion of the declining movement. Through 1944 the
air attack did not prevent the army from originating such movements,
although the time of arrival, or even the arrival, of units and equip-
ment became increasingly uncertain. Couriers accompanied detach-
ments and even shipments of tanks and other weapons; their task was
to get off the train when it was delayed and report where it could be
found. After the turn of the year, even military movements became
increasingly difficult. The Ardennes counteroffensive, the troops and
equipment for which were marshaled- over the railroads, was prob-
ably the last such major effort the Reichsbahn would have been ca-
pable of in the West.
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II. The Air War Against Japan
At the outset of World War II the Japanese economy was relatively
small, approximately 10 percent the size of that of the United States.
Despite great efforts to increase the availability of raw materials from
domestic sources, Japan was highly dependent on imports to main-
tain its industrial plant. The acquisition of Manchuria and parts of
China helped materially in alleviating Japan's shortages of coking
coal, iron ore, and foodstuffs, but negligible quantities of iron ore and
bauxite were available within Japan's "inner zone." Plans to develop
a synthetic oil industry failed to yield significant results, and Japan
was almost wholly dependent on imports from the Dutch East Indies.
The same overseas dependence existed for rubber, ferroalloys, and
manganese as well as for a variety of other militarily important ferrous
and nonferrous materials.
Japan's strategy had been based on the accumulation of munitions,
oil, aircraft, and ships which could be thrown into action against es-
sentially nonmobilized enemies. The expectation was that the dev-
astation of the initial blow would result in the enemy suing for peace.
A. THE AIR ATTACKS AGAINST JAPAN PROPER
Most of the tonnage of bombs dropped by Allied forces in the
Pacific War fell outside the Japanese home islands. Only one-fourth,
or 160,000 to 170,000 tons, was dropped on Japan proper, mostly by
B-29's. In contrast, 1,360,000 tons were dropped within Germany's
own borders. The air attack on Japan came very late in the war
and was very highly concentrated. From June 1944 to January 1945,
only 800 tons of bombs were dropped by China-based B-29's on the
Japanese home islands. Following the seizure of the Mariannas in
August 1944, a series of bases for long-range bombers were constructed,
but the tonnage dropped by 9 March 1945 totaled only 7,180 tons.
The basic revision in the method of B-29 attack came on 9 March
1945, when it was decided to bomb the four principal Japanese cities
at night with incendiaries. The first attack burned out 15 square
miles of Tokyo's most densely populated area. This enormously
destructive attack was followed almost immediately by strikes on
Nagoya, Osaka, and Kobe. In the aggregate 104,000 tons of bombs
were directed at 66 Japanese urban areas, or about two-thirds of the
total tonnage dropped on the home islands. Far smaller tonnages
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were directed against selected indus~riai an.1 military targets, as fol-
lows: 14,150 tons against aircraft factories, 10,600 tons at oil refineries,
4,708 tons against arsenals, 3,500 tom against miscel'ar.eous industrial
targets, 8.150 tons at airtie._cs, and 12,054 mines u-2d in the attacks
against shipping.
B. EFFECTS OF THE ATTACKS
The Anhysical destruction resulting from air attar i.s -in Japan was
approximately the same as .hat suffered b'i Germ,-n, . The attacks
were more concentrated in time, and the tz.iget ari-.as n Japan were
smaller and more vulnerable. Japans defensive capabilities were
.,iverwheimed as was its will and cat:acity for reconitiuction and dis-
persal. Some 40 percent of the built-up area of the hf cities attacked
was destroyed, and about .31) percent of the entire urban population
lost their homes. Total civillian casualties a~ the res~ilt of nine months
of air attack, including an estimated 200,00) frDm the atomiic bombs,
were approximately 806,001). These casualties p: of 1ably exceeded
those which Japan, suffered :in combat.
The economic effects of the air a::tacks are :lifli+, il to specify be-
cause the loss of merchant shippini, had essentiaaty isolated Japan
from its sources of indusi:rial raw materials. Most r f +e- oil refineries
were out of petroleum, the aluminum plants were t tit of bauxite, the
steel mills were short of ore and coke, and the mur: iti ins plants were
low on steel and :aluminum. Japans economy war- in Large measure
being neutralized twice over, first 1),i cutting off ii ,p, )rts and second
by air attack.
The railroad system was riot surrject to substant :ti attack and was
in reasonably good operating concition .t the t inc of surrender.
Jpan's electric power system had not been selech as a target sys--
(erri, largely because it existed in numerous small pi (A uCtion facilities.
Therefore, most of Japan's generating ant distrib rton capacity :re-
ir_amec operable. An exception was in it.e urban areas which had
been subject to heavy incee:udiary attack.
C, CIVILIAN MORALE
lime early Japanese military succ,csses, 1 articuia_ i% the capture of
Singapore, were followed 1)'' a wave of optmism ai,ct high confidence
no the part of the Japanese people. As the war )r agressec , subse.-
=: cent defeats were studiously withheld frcm the I~ooopie or disguised
as strategic withdrawals. The US Strategic bombi:4g Survey reported
that as late as June 1944, in spite if an iimcreasin...; . h:ortage of food
12 SECkET
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and exhausting work to support the war effort, only about 2 percent
of the Japanese population believed that Japan faced the probability
of defeat. The beginnings of attacks on the home islands coupled
with military defeat in the Philippines and a continuing deterioration
of food supplies began to be reflected in sharply lowered civilian
morale. The survey reported that by June of 1945 nearly one-half
of the Japanese people believed that victory could no longer be
achieved. One striking effect of air attack on the cities was the mass
evacuation which resulted. Roughly one-fourth of the urban popula-
tion either fled or was evacuated. Progressive lowering of morale
was characterized by loss of faith in military and civilian leaders,
loss of confidence in Japan's military might, and increasing distrust
of government news releases. The interrelationship of military, eco-
nornic, and morale factors was a complex one, in which the urban at-
tacks had played an important role. It should also be remembered
that the effect of the atomic bomb was severe not only on the civilian
population but also on the civilian and military leadership.
D. DESTRUCTION OF JAPANESE MERCHANT SHIPPING
Japan's merchant fleet was a key link in supplying home industry
with raw materials as well as being vital to the support of armed
forces in the field. Approximately 9 million tons out of a total avail-
ability of 10 million tons of merchant shipping (including ships of 500
tons and over) was sunk or seriously damaged during the war. About
55 percent of this loss was from submarines and approximately 10
percent from mines, most of which were dropped by aircraft. Most
of the remainder fell victim to direct air attack. Thus the role of
airpower in the isolation of the Japanese home islands was a major
one, even though it was secondary to that of the submarine (see
Figure 2).
As a maritime nation with large domestic and foreign trade, Japan
had developed a modern merchant marine of first rank. Because
shipping was highly developed and heavy industry was located to use
fuel and raw materials received by water routes, the railroad mileage
was small and the rail system of ? limited capacity. Only two main
rail lines extended the length of Honshu Island. The fleet of large
oceangoing ships was complemented by numerous smaller craft en-
gaged in the coastal trade in and around the home islands.
The conquest of Southeast Asia gave Japan control of most of the
world's supply of rubber, tin, antimony, jute, and quinine as well as
sources for more than enough of its own requirements of petroleum,
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iron ore_ bauxite, sugar, c.ortl, and rice. .trurin~, the liar, japan drew
heavily on this area for die bulk raw materials needs :i ov its industry.
respite a vigorous hiuk Ting program, japan at, .i 1942 was not
able to maintain the prewar level of total tonnage ! nerchant ships
afloat. The December !'_9"_1 level x as 5.4 iniiiion I.I is of :merchant
excluding tankers. .% year la el, fist,, total i :.u been seduced
s
,
r liilion tons, ants by December 1.943 the cot rt ination of ub-
rr1aruie and air attacks lead lowerec snip availabii , to 4.2 million
-is. he submarine o tertsive had been Farticula rv stepped up in
LAC. fail of 1943.
Y 'w { car 19444 sa m the be inning )f the ttevastat ~ carrier attacks
clrier raids on
I-ant sh:ip;oing, 0rigii11aliy as a resudt or tit c
I r,uic and Palau. A series a operati,)ns involving 1 invasion of tide
rrianrias and the premva ion carrier raid, arout tlie Piiaaiippiiies
t,we:_i in the summer and. the tall sorties agau, ;: merchant ship-
:
sst;, flown by Army, Na tiy. itLd i1-iarine !aria-baseti ,t ti carrier-based
i.irc raft increased frorn l U ,(06) in 1114` to : ~`7, JOb 11 1944. in 1945
in
con at;irled sorties neat tact. a nett rattily )eat: of ,, most 51,000
p il, During N44 the merchant tonnage ah:)at Ad been rec aced
,)vcrr 5C, percent in a 1-2--:nerttf:L perio,1 and was ona: i )out 1.5 mission
ia_ o._ wheii lapai1 sl.rreiu!eied.
)ther air operations mid ca. signthca.nt e test in rt n rF ttg the mobility
era -_1. slunnkin.g merchant fleet der pate ) r.part s V J Agness to take
:1 va re ,hipping losses i ec .use of its despe)ate rtes or strategic im-
)ris. 1'he mare iayilrz; ca]npa get oonducied by tN b-29 s early in
In f only reduced ti ;c (: ta.l tonnage of merchan s tipping but also
katled certain i port, ,: ::: d great. V retie red tin erviceai)inity of
nr)orts passed tine.-ir peak in August A ~i4L.
ost it significant number of its rankers at t'ru.11
it :gs of tankers created cesperate sil(Irtage Of fuel
fay ApA-ii 1945, tanker irliv)crts ceased completely.
drawn down and were q~liciKly exiiausteo, the ri,
industry 'Uegair i,: dry up, anti Lt coriSi(
ships was Lid 111) i 1 lack of pet.ruie.ntn. 1.1
stockpiles of 1r dt strial ran inak r ass, eve
horns r!.icitistries surfer-6 serious iu 5e5 114 output
i terdiction of Inerchaii
Secii.ned 76 percent in a
xite imports.
t Japanese Navy
,m d furtiier sink--
tae fall or 1.944.
tucks had ieen
1 suppLLy for the
r tlhie tr nilage of
.1 site the accurnu-
he direct muni-
a restlt of the
sltil)pin 1:f or example, a cu:nimttai output
single -4enii' a6 a result t.:i.e stoppage of
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Finally, the nation became short of food. Local production had
declined, partly as a result of cutting off imports of fertilizers. Fish-
ing, a major industry prior to the war, was reduced by 50 percent for
a variety of reasons, including requisitioning of ships by the Japanese
Navy and the shortage of fuel. The situation became so acute by
April 1945 that virtually all of the small remaining shipping capacity
was diverted to the import of food and salt, sacrificing the trickle of
industrial raw materials that had still been flowing in. By April 1945,
Japan was essentially isolated. The raw materials base of its economy
had been cut off, and the country could look forward only to gradual
starvation and increasing military impotence.
E. ACTIONS OF THE ELITE TO END THE WAR
Although in theory the Japanese Emperor was the sole authority, in
practice he usually approved the decisions of his advisers. During
the early years of the war these advisers were dominated by fanatical
army and navy officers. The first definite breach in the political coali-
tion did not occur until Japan's defeat at Saipan. Ten days later,
on 16 July 1944, the Cabinet headed by General Tojo fell.
Tojo's government was succeeded by one headed by General Koiso.
Despite the original instructions to the Cabinet to give "fundamental
reconsiderations" to the problem of continuing the war, Koiso was
unable to stand up to the more determined military officers. His
major accomplishment was setting up a Supreme War Direction Coun-
cil which was the inner cabinet group through which the problem of
surrender was eventually resolved.
The conviction and strength of the peace party was increased by
continuing Japanese military defeats after Saipan and by Japan's
inability to defend its airspace against attacks in late 1944 and early
1945. After the US landing on Okinawa in April 1945, General Koiso
was replaced by Admiral Suzuki.
In May 1945 the Supreme War Direction Council began active dis-
cussions on ways and means to end the war. The Council initiated
discussions with the Soviet Union seeking mediation. On 20 June
1945 the Emperor on his own initiative called the Supreme War Direc-
tion Council together and ordered it to develop a plan to end the war.
August brought the decisive steps, with the atom bomb falling on
Hiroshima on the 6th and the USSR entering the war on the 9th. The
Emperor quickly resolved the conflict in favor of unconditional sur-
render.
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In retrospect, it is clear treat, at the highest levels witi in the Japanese
i;ahinet, the movement to [)r-:rig the war to ai end be;aa over a year
I~aarlier than the date of the fi.:_ial surrender. Japan's sin ender cannDt
be imputed solely to any One of the mnmerou;; revers,, is which jointly
c)ntrihuted to the final decision. The military rever,,al; in the field:
Ile destruction of the Japa_aese fleet and merchaiv riarine., which
-,dated the home islands.: the surrender of Germany the destruction
caused by incendiary ana .t,)mic weapons; and, fin a] y, the Soviet
Decision to enter the war, all played a part.
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III. The Air War Against North Korea
A. INTRODUCTION
The lessons learned in one war against an adversary using strategy
and tactics appropriate to the time and place cannot often be applied
with success to another war fought under different conditions. Im-
proved weapons alone can negate the lessons of an earlier war. Fur-
thermore, each war is unique in its total setting-the political and
economic realities of a North Vietnam are not those of a North Korea
any more than the tropical setting of the former is equal to the harsh
climate of the latter.
This section places particular emphasis on the attempts by US
aviation forces to interdict the transportation system and to destroy the
heavy industry of North Korea. In spite of the differences between
North Korea and North Vietnam, these aspects of US operations in
North Korea are relevant to current US air operations in North Vietnam.
B. SIMILARITIES AND DIFFERENCES OF ENVIRONMENT
Numerous similarities exist between the present war in Vietnam
and the Korean War. Each conflict involves a divided country. Com-
munist China looms over the northern border of both North Korea
and North Vietnam as a supplier of war materiel and as a participant
or potential participant. Many contrasts exist also. The topographic
and climatic settings of the military actions in South Vietnam are unlike
those fought in Korea. Instead of the guerrilla and infiltration tactics
characteristic of today's war in South Vietnam, the Korean War even-
tually involved large-scale land armies.
Other contrasts can help put the two conflicts in perspective. North
Korea occupies an area of about 47,000 square miles and in 1953
had a population of 9 million; North Vietnam has an area of 61,000
square miles and a population of 18 million.
C. INTERDICTION IN NORTH KOREA
1. Introduction
In the summer of 1951 as talks about a truce began and the fighting
lulled, the US Eighth Army calculated that enemy forces in Korea
were stockpiling daily 800 tons of supplies behind their lines. It was
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II ;aced that the enemy wr,i l(l reach a degree or .,r traredness pre-
1norrs1y rnnaralleled ire tin Korean War, ' To ,r Jere with this
~rlailclun, he Far East Air force (FEAF) nl:anned a na-ration Strangle.
=t (?(impreh.ensive interclrei:uon camniign arra.inst N r'h Kor(a',; rail-
r'()ads and highways.
( trer~rtion Strangle had ~.v(-1 prime pal oh ectives_ the knocking
it of tbire North Korean r-a i! ;vstetn by ma.inl ain ng It tuner rail cuts
n gettir,g a bridge bat in partial opera-
lion so that some supplies could begin to flow agar although traffic
1Uight remain far below capacity levels.
The North Koreans and Chinese stationed rai rim i. construction
troops along all main supply routes which were ur ter attack. Units
,of 50 troops were located at all major rail station, nd crews of 10
,nen were located every ~. miles along tit(! route. 1n addition, rail
walkers spotted damage to the rail (Jr roac_bed. l'- e< rbv inhabitants
were recruited for common. labor, and soraetimes as many as 1,000
,Persons were used to repair a damaged sect. on. r"vi (I tr c, experienced
railroad construction crews would move in and _nak- tiie actual repairs
c the rail line. Furthermore in portage-l:ke operations, rail service
was maintained on very short stretches of usable trr:ct.---as short as 11
tniles-and freight was unloaded, ca-ried mound ra.1 ,tits or damaged
bridges, and then. reloac ect on another trai i.
it, Highway Interdiction
The road network ri, ~~nrth Kom ea, originally le velopeci by the
Japanese. had always been of secondary iriportani e to the railroads.
t'rucks had been used typically for short hauls and se ?ved as links be-
e veen industrial and commercial centers and th ? major railroads.
North Korea's principal Jhighways roughl,> fullov~~cti the major rail
routes from Manchuria southward. Altogether ab,~ tit 10,000 miles of
Highways existed, at best surfaced with gravel or c u: bed stone.
,,although the major interdiction effort of Open tun1 Strangle was
against: the North Korean system, attacks agar, r ;rucks were also
ruresse(t, especially night attacks led by B-26's i )ne occasion, an
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Air Force wing reportedly sighted 3,800 motor vehicles and attacked
2,600 vehicles in one day. The Air Force claimed that 6,400 trucks
were destroyed in October 1951 alone. Highway bridges were also
attacked but proved to be more difficult to interdict effectively than
rail bridges. Bypasses were sometimes built at a considerable distance
from the original bridge and were thus not easily sighted; fords were
built and used during much of the year.
Truck traffic was uncommon during the daylight hours and at night
was hard to locate and to attack effectively. The results of night at-
tacks against motor vehicles as well as rolling stock were especially
difficult to assess. Trucks usually traveled in convoys of 15 to 20
vehicles, ordinarily under blackout conditions. The mileage norm
for trucks per night was about 60 miles. For example, a round trip
from the Manchurian border to the battle zone required about 10
nights' travel.
d. Night Operations
Even before Operation Strangle began, the North Koreans had
started to move virtually all rail and road traffic at night. The B-26
bomber was used extensively as a night intruder to harass trucks and
trains along major enemy supply routes. During Operation Strangle,
1,500 to 2,000 sorties were flown monthly by B-26 bombers, about 90
percent of them at night. The heavier B-29 bombers were used to
attack targets at night.
In the absence of bright moonlight, B-26 attacks achieved only
limited success, and numerous experiments were conducted with flares
to light the targets. Infrared detection systems were used on a limited
scale to locate targets such as locomotives, tanks, vehicles, and indus-
trial locations. The results of these innovations were limited, however.
In 1952, as Operation Strangle disrupted railroad lines, the North
Koreans and Chinese made more intensive use of trucks to transport
supplies to the front. In the fall and winter months, sightings of
vehicles declined, and the B-26 night attacks were shifted to rail cut-
ting and to harassing North Korean night repair activities.
The major lessons from US night-intruder operations during the
Korean War were the following: (1) aircraft, especially the B-26 that
had been designed for day operations, had only limited success at night
in detecting, identifying, and attacking moving targets; (2) air crews
required careful selection and special training for night operations;
and (3) a strong need existed for a family of "denial" weapons that
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w could successfully interdict rail lines and hig:wa? s for periods that
Would eliminate the need for essen:ially inefficient r i!2.ht operations.
Night operations were hampered throughout by `he inadequacy of
night photography to provide adequate assessment o1 bomb damage.
e. The Wa.-dong Chokepoint
The Korean War offers an exceller_t example of tie lifkiculty of sue-
cessfully interdicting a transportation chokepoint b, I i:rge-scale aerial
bombing. In the winter of 1.952, while Operation SitLrate was getting
under way, target specialists located what appeared ? o _)e a vital choke-
point near the village of Wa-dong in cen:ral Kona about 20 miles
north of the 39th -parallel Here a major east-wi. t railroad passed
over a highway from W i aisan on the east coast t( the capital at
P`yongvang. About 100 v,rrds further to the west t e railroad entered
a short tunnel. The railroad and highwa i did i t follow- identical
alignments across North Iti_c:rea but came together t ly at Wa-dong.
docent frills rising to about 300 feet above the :'a ley floor would
have made Wa-dong stand cut as an ideal choke rc int to even the
most unimaginative target analyst. The North Kore- ors had used both
the lateral highway, and the railroad to shuttle sur_'plies between the
cast and west coastal railroads. thus substantially a rc -easing the flex-
ahility of the badly damaged, rail system. Jhe objeati-e of the attacks
was to block all rail and vehicle rncvernen: in the ar ~a. Due to the
area's rough terrain, b-ypassing the choke joint w u _d have proved
very costty.
'=:)r 44 (lays, from 26 lanuary to [1 March 1952 i 7 B-29 and 1.26
i3-26 sorties saturated the target of about 18 acre Ivi.th 3,928 500-
i)ound general-purpose boraos, one Lomb n.r every 32 square yards of
target. Bomb assessment reports ror 24 (lays of _h ! 44-cday attack
period showed the :following results:
l ailr )ad
Serviceable .... ..
io days
ilriserviceable
8 dais
Status unknown ..
6 c aps
,'otaf
:%4 'iat. s
liign!vay
S-_viceable
15 days
ila:nservieeable
4 days
St tus unknown
5 (jays
"r)tal
i'4 tats
l:iorn h assessment repor :s also revealed that th' ` :oLal effort had
n?e:sulteel in only 18 actual rail cuts ~Lnd 15 higlawa cuts. The effort
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 Approved For Release 2007/10/23: CIA-RDP78T02095R000800070002-2
at best resulted in the railroad being interdicted for 8 days and the
highway for 4 days. Except for temporary disruptions the North
Koreans had suffered very little damage. The bombs had done little
more than churn up the countryside; landslides that had been hoped
for did not occur.
Evaluations made of the Wa-dong experience during the Korean
War led to the conclusion that it is a fallacy to assume that there is an
"area target" for traffic interdiction, and the Far East Air Forces recom-
mended that airpower be concentrated on pinpoint bombing against
definite targets in preference to area bombing in any future interdiction
attacks.
D. STRATEGIC BOMBING
1. Early Bombing
North Korea's modern industry, which was developed by the
Japanese, was considerably greater in total capacity and range of out-
put in 1950 than North Vietnam's industry in 1965. During the initial
months of the Korean War the B-29's available in the war theater
were engaged in close tactical support of the hard-pressed US and
South Korean forces. Attacks on industrial targets in North Korea
were not feasible until mid-July 1950. In the next three months the
FEAF Bomber Command dropped 10,400 tons of bombs, with ex-
cellent results, on the major targets listed in Table 3. Of 20 strategic
targets designated by the JCS, 18 had been destroyed or severely
damaged by the late September.
In September 1950, plans were under way to destroy the modern
complex of hydroelectric generating plants that had been built by the
Japanese. On 26 September, 17 B-29's attacked and inflicted minor
damage on the Pujon Hydroelectric Plant, which had an installed
capacity of 128,000 kilowatts. The same day, however, the JCS sus-
pended attacks on strategic targets.
By late September the Commander of FEAF was able to claim,
"Practically all of the major military targets strategically important
to the enemy forces and to their war potential have now been neu-
tralized." In a few weeks, North Korea's modern industry had been
destroyed. Although such destruction obviously inflicted "punish-
ment" on North Korea's leadership, the military effect of the strategic
bombing was of little consequence. Military equipment and ammuni-
tion continued to flow into North Korea from China and the USSR.
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 Approved For Release 2007/10/23: CIA-RDP78TO2095R000800070002-2
,-4t rategic its a tta(hE it 1u A of 191 2iorea
11 a,_'-t ~11.~' ( ni -fill, 211 1r1:5U1tr i'
ii 113; 1~`: _ shops 11_]x! v ard,
haiay shops an'i ards.
card=
244
112
417
1127
o!)ti
563
,n 4 11 1~_ct) o=l11'( utpan .
51)) )
MO
311
,:ji ,, .y shot) arri cards . -
111
(1
l~ongjin...
Halh-lr a ?,d suhil ar11c hast?.
249
j
I32
I f.. ti r ark:~
21;3
f
1)63 49
\t 1
l;a;,hil
t -r:
O
1S
.
Nigl
9 lll.d shops aria: ',arris
11 [1
.
tit t.
Ma -,at rig
'(tl l - t i l t ) ti l a r l i e m s ,
cgt
24ti
284
r 1
...
C;;an~jtagalh I ! Pup-i; 11.~.lroelociw Plant No.
lh)rnliun [tali, c :lop i a it <
~'as.117t .. ho- 11 'ittn.) - n _;x;)lorty~ s i v:up8r1)`.
3r) lit
368 Ili
it':g earl .
.,dp=:+, ?Il. i _1111 5. :ca, 110[)5 al !. Y--{rt !.,.
+'ii)tlgJ ul_ _ _ . _ 81 9 vojr-s.
tangdok....
luntn"ongiii
luulgj11
h:irla.-
'.11T1Ci1)rl_
e:rt,
'I',I]?gct
l,la;.tt ' is tJil htora~e. - . .. - 2 `
i, 11it.=ay dhcpr au%~ cards. ~r i) ])
atrh a.tl..g taros . - .. . . .Ii) all
i.tr . uc.a iudustrr and I :ursl ali?_l~. 1138 :31)
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 Approved For Release 2007/10/23: CIA-RDP78T02095R000800070002-2
2. Later Strategic Bombing Efforts
a. Hydroelectric Power
It was not until June 1952 that the hydroelectric installations pre-
viously regarded as "politically sensitive" targets were again considered
as legitimate targets. Over a 3-day period in June 1952, 730 fighter-
bomber sorties by the Fifth Air Force, supported by sorties from a
Navy Task Force, were flown against the power complexes, including
the Sui-ho Generating Plant on the Yalu River. Poststrike evaluation
of the bombing attack indicated that 90 percent of North Korea's elec-
tric power capacity had been knocked out. For more than two weeks
there was almost a complete blackout in North Korea until small
thermal plants and undamaged hydroelectric plants restored a small
portion of North Korea's pre-attack capacity. Although the small,
dispersed "war-industries" in North Korea obviously suffered from the
loss of electric power, the extent of the damage to industry in Man-
churia, which received much of its electric power from North Korea,
was difficult to assess.
Attacks against the hydroelectric installations came much too late
in the Korean War to have much impact on the outcome or to do serious
damage to North Korea's war effort. The attacks were designed
primarily to exert continued air pressure on the North Koreans and
Chinese to accept UN truce proposals.
b. Irrigation Dams
In the spring of 1953, only slow progress was being made at the
Panmunjom truce talks. Air Force targets specialists seeking addi-
tional means of increasing air pressure against the Communists recog-
nized the importance of the irrigation dams to Korean rice production.
There followed a large-scale and highly successful attack against a
2,300-foot earth and stone dam about 20 miles north of P'yongyang.
Along with severe damage to a major rail line, the floodwaters also
damaged 5 square miles of prime rice crops.
Other Korean dams were attacked by US fighter-bombers and B-29's,
ostensibly to interdict transportation lines. These later attacks were
less successful because the North Koreans, as in other circumstances,
improvised countermeasures. For example, by rapidly lowering the
water level the North Koreans made it much more difficult to destroy
or seriously damage the dams.
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SECRET
E. LESSONS FROM THE KOREAN WAR
1, Introduction
The 27,900 strike sorties flown and the 34,300 tons of bombs, napalm,
and rockets expended under the Rolling Thunder 3 arc gram from Feb-
ruary through December 19665 are less than )ne-thir l t -te 81,600 sorties
flown and the 1,04,000 tons of bombs dropped by th? v it Force during
the interdiction and armed :reconnaissance ;orties i.1 tie 11 months of
Operation Strangle, In addition, during tie Kore.tn War Navy and
Marine aircraft operating from carriers prcbably aisc dropped about
one-third as much tonnage its was dropped by the \ii Force on inter-
diction targets.
Even allowing for exaggerated damage c.aims, it is clear that there
were far more lucrative targets in North Korea than a:?e being located
and destroyed presently in North 'Vietnam. Destruc t:ion claimed in
the 11 months of Operation Strangle in Korea compared with that
claimed for Rolling Thun(---!er in Vietnam through December 1965 is
shown in the following tabulation:
OPEI ATIGN Sr LANG:,E
,m I,r:ac THUNDER
locomotives
27
6
Freight cars
?,638
227
Vehicles
332,210
483
Bridges ...
22:3
161
3uilding3 .. ...
9,109
1,837
13arges and boats ...
....
225
461)
The greater destruction achieved in Korea comaa1 ed with North
Vietnam is not solely a function of the number of s4 rti es and the tan-
nage of bombs dropped. The Rolling Thunder pr,g1 am has had to
operate under policies which sharply limit both the ai eas in which it
can operate and the targets it can attack. N:)rth Ko -ea's railroads and
highways had to supply a.!most 1 million _roops, 300,000 of whom
w sere at the front. North Korea had almos: 2,300 : ni es of rail lines
and 10,000 miles of highways, compared with North Vi, 41-1am's meager
485 miles of rail lines and 5,800 miles of hig sways. N )rth Korea had
a much larger park of both rolling stock and trucks n addition, al-
though the population of North Vietnam su )stantia''.ly exceeds North
Korea's, there was more modern and seminlodern i idustry in North
Korea than is found in North Vietnam,
2. Failure of the Interdiction Campaign
At the time Operation Strangle was under way., Rt was estimated
that each Chinese division required 50 tons of supplies pE:r day.* With
About 48 percent food; 22 norcen- clothing, weapons, and equir ago; 10 percent POL;
aad 20 percent ammunition.
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60 divisions at the front, approximately 3,000 tons of supplies had to
be moved from Manchuria to the battlefront each day.
Peacetime capacity of the double-tracked line in western Korea
from Sinuiju to P'yongyang was estimated to have a capacity of from
6,000 to 9,000 tons per day. After maximum interdiction efforts, it
was conservatively estimated that only 500 to 1,500 tons per day were
getting through to the battle zone. The capacity of the east coast rail
line, 5,000 tons per day in peacetime, was reduced to less than 500
tons per day. Thus railroads were still able to transport about one-half
of the daily requirements. In addition, the North Koreans and Chinese
also relied heavily on trucks and on peasants carrying supplies strapped
to A-frames and even bicycles for.moving supplies to the front. A
staff study completed in April 1952 by two Air Force officers concluded
that after seven months of maximum US effort the Communists still
were more than meeting minimum supply requirements. The study
concluded that the accepted figure for the enemy's minimum supply
requirements was 2,700 tons per day under existing conditions but
that more than this amount was being received. The staff study also
stated that over and above daily requirements the enemy had been
able to stockpile approximately 100,000 tons, or a 37-day supply, dur-
ing the seven months of the rail interdiction program. This capability
was, however, not sufficient to permit the North Koreans and Chinese
to mount sustained offensive operations.
Another logistics study from the Korean War illustrates how difficult
it is to prevent what was called "seeping resupply." During three
months in the winter of 1951-52 the Chinese and North Koreans were
firing 15,000 mortar shells per month, or 500 shells a day. Each shell
weighed 10 pounds; thus it was possible for a peasant to carry five of
them on an A-frame. One hundred peasants arriving at the front from
supply depots in the rear could supply all the enemy's daily needs for
mortar ammunition. One truck a -day could replenish the supply
depots.
Operation Strangle clearly did great damage to the transport system
of North Korea and conceivably prevented Communist China from
mounting additional large-scale offensives in Korea. At the same time,
it is also clear that the Chinese and North Korean troops received suf-
ficient logistic support to contain the offensive pressures exerted by
the Eighth Army. In short, the defensive capabilities of the Chinese
and North Koreans showed no sign of collapsing as a result of the inter-
diction campaign, and indeed the enemy was able to mount sharp
battalion-size attacks on occasion.
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'l'hc air interdiction cara.)aign failed to ,_lenv Cl, :-,)nunist forces the
supplies they neected to contain the ITS A ?rny hec "n .e the North Ko-
reans and Chinese were ahle to take effective crnr krn,)easures. One
r-,ra;or lesson that emerged from the Kr rrear War iv ,s chat US planners
rsnderesti natec. the effectiveness of the enemy cor, te rmeasures. The
North Koreans and Chinese showwerl incre, sing rah idity in rebuilding
damaged rail and road bridges and other key in -a'lati.ons. Choke-
Courts, often given. exaggerated importance. were I er rtenth bypassed
Without rrndu.e enemy effort. I)arkrtess shioiided i r,, t of the enemy's
clovenlents from effective attack, r?e rnaioi lesson the Korean War
was the clearly dernonstratecl need for the (level( )nient of a f ,tnily
of weapons that could s;nct.essfully interdict night --a Iroad and high-
vrav traffic.
3. Air Pressure Tactics 0111 Psychoiogical Warfare
ti: is cii ticult to jiicke the (ver,111 effect of IT rterdiction and
strategic bombing en the will of the politic-
,a leaders iii and the morale
of the civilian pop'Ilatirrrr of North Korea. Ther,r- are nnnlerous ex-
arnples, however. of the Nr)rth Korei_ns and Chine. , 'esponding with
'iJ'ecti e c )i ntermeasuros Ic each new phase 0` air )reratlons against
North Korea. 1 h-e North Koreans were all, to dci e effective mans
#r:J)uirtel act the r)rogrrn- of: massive rail interdir tip rn, The North
Korean response to the im-rnhin.r of irrigation dims Cho illustrates the
tenacity and cleverness -vvitl which he Cornmiinist riet new phases
GS air operations.
[rrs ny so-sine historians that a r oneritions v Fri almost solely
i?esponsibie for the North Kerreans and Chin ace initr 11 , coming to the
r?trnference table and fin, ll ;i>rninv r truce ii reeror 1U cannot he srrh-
tl-intiate',d.' The Chinese and North Korr=t c ream,- a,, the conference
Iit! le mainly became their total l(Sse, a.cr ruing I 11 the w,var had
f ecome greater than their ~eotal vaqp,, .ail military 4 r>l~Heal and ceo
_omic factors considered, -i'1-ludic r oc;es Iron!: ai 't inks, I' air-
a.+ower played an important --cote in (r)rviricint; the C, '-:r ),.nists to .Tonle
i.e terms, but the ev rile ,,-'e sloes not srrpnort the , that airctrikes
),were the decisive factor,
h,calise of a host of i actors, inch (hr t to, rmi,'r nature of _TN
,rlolice action" in Korea and tie
liner-air) Tir)'ition of officials about
ac advantages and disa~lvvantages o+~ nwch?logieIt! ;t r warfare_ the
is Ac E'rrce historian for e,; rmr,te, in ,lis,-,rss n.u FF.AF c,po -,
atio,, n k" area in mid-1352,
the rlestrnctive fore, of Ft A
lk' s ai"pnwf'r has broker the stal-;5
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psychological warfare phase of US operations in North Korea was
little understood and only intermittently applied.
4. Lessons for Vietnam
The lessons from the Korean War indicate that it will prove difficult
to cut off supplies flowing from North Vietnam to South Vietnam. The
total daily tonnages needed by the Viet Cong and North Vietnamese
regulars engaged in South Vietnam are far less per man than was the
case in Korea, largely because most food and clothing supplies are
obtained locally in the South. Relatively small numbers of trucks,
carts, and human bearers can maintain more than the enemy's mini-
mum requirements unless the Vietnamese war is sharply escalated.
Furthermore, the experiences of the Korean War suggest that as long
as they continue to receive extensive support from China and the USSR
the North Vietnamese are likely to show an increasing capability to
improvise countermeasures to circumvent a continuing US air inter-
diction. The Korean War suggests also that diminishing returns can
be expected from continuing air interdiction. At the same time, the
increasing effectiveness of conventional antiaircraft weapons and air
defense missiles could raise the cost of continuing the campaign. The
rebuilding of bridges, the building of bypasses, and the other counter-
measures in evidence in North Vietnam in no way suggest a less de-
termined enemy than was encountered in Korea. The primitiveness
of North Vietnam-the lack of potentially decisive military and indus--
trial targets-will make it difficult if not impossible for airpower alone
to extract a prohibitive price for North Vietnamese intransigence.
Only the application of large numbers of new interdiction weapons
which are more effective than those that were available in the Korean
War would be likely to tip the scales in favor of successful, long-term
interdiction.
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Munitions
Production
Bombs
(Thousand tons per quarter)
Effect of Allied Bombing on German Munitions Production
Munitions Production
(Average month 1941 =I 00)
Bombs Dropped
1942 1943 1944 1945
E-1 Effect of Allied Bombing on German Munitions Production
Munitions
Production
Effect of Allied Bombing on Japanese Munitions Production
and Maritime Shipping
Munitions Production
(Average month 1941 = 100)
Bombs Dropped
aeaaorne ,ram, oy ..win
Merchant Marine
Bombs 5~>ouorne iratiic
(Thousand tons ( thousand metric
per quarter) tons per quarter
1941 1942 1943 1944 1945 1946
E-2 Effect of Allied Bombing on Japanese Munitions Production and Maritime Shipping
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Indexes of Bombs Expender and Value of Destruction n the Korean War
During Operation Strongle
August 1951-June 1952
"~?'r~ Index of Bombs Expended (Tons)
Index of Damage per Ton of Bombs
Index of Value of Destruction
C?
Aug. :Sept. Oct. Nov.
1951
Dec. I u Jan.
Feb. Mr1r. Apr. May June
1952
11;-3 Indexes of Bombs Exnenced and Va_ue of E estr rtio: hit the Korean War
burin , Operation Strangle
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SECRET
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