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Fwd: FW: (ai) Planning Air Operations: Lessons from OperationStrangle in the Korean War
Thought this might be of interest. Published in 1992
Subject: Planning Air Operations: Lessons from Operation Strangle in the
Published Airpower Journal - Summer 1992
Approved for public release; distribution is unlimited.
Planning Air Operations:
Lessons from Operation Strangle in the Korean War
Lt Col Michael A. Kirtland, USAF
OFTEN THE lessons we learn best from combat come not from our victories
but from our failures. Such a case is the Rail Interdiction Program,
better known as Operation Strangle, conducted in Korea from the summer of
1951 to early 1952. Enthusiasm for air power and the desire to show that
air power was enough to win a war were not enough to make up for
deficiencies in planning, command structure, or resources that plagued
this operation. The lessons those airmen learned so painfully, and at such
a cost, forty years ago are still relevant today. Effective air operations
come from understanding one's doctrine, knowing one's limitations, and
most of all, from thoroughly planning the campaign from beginning to end.
The Korean War began with a surprise North Korean attack against the South
on 25 June 1950. The woefully unprepared and battered South Korean army
rapidly retreated. US military forces were introduced almost immediately
from Japan. Unfortunately, they had served since the end of World War II
as an army of occupation in Japan and were not ready for the difficult
combat they faced in Korea. By late summer of 1950, the 100,000-man
Republic of Korea (ROK) army had lost over half its strength. US forces
brought over piecemeal from Japan were sent directly into the fight and
did not fare much better. North Korean forces had reduced the ROK/US
control over the Korean Peninsula to a small area around the port of
Pusan--the now famous Pusan perimeter.1
American air power, in the form of Far East Air Forces (FEAF) and Fifth
Air Force stationed in Korea, was not much better prepared for war. FEAF
planning for Korea consisted of assistance in the evacuation of Americans
in the event of war.2 But air power recovered much more quickly than did
the land forces, scoring its first aerial victories just two days after
the opening of hostilities.3 Air Force action quickly destroyed much of
the North Korean air force, reestablishing air superiority. FEAF's Bomber
Command began bombing missions over North Korea. Fifth Air Force fighters
supported land forces by attacking enemy formations on the ground. Between
Bomber Command raids, close air support by Fifth Air Force, and a truly
heroic stand by US Marines and Army units around Pusan, the enemy assault
was finally slowed long enough for United Nations (UN) forces and US
military reinforcements to arrive.
Relief from the pressure on Pusan came in September when Gen Douglas
MacArthur launched a daring invasion at Inchon. Within a week, US forces
had broken the enemy lines around Pusan and linked up with units of X
Corps that had landed at Inchon. It was now the North Koreans' turn to
head into full retreat. By late October, UN forces had driven the enemy
back into North Korea, decimated his air and ground forces, and occupied
the North Korean capital at Pyongyang. By mid-November UN forces were
approaching the Chinese border along the Yalu River.4
UN forces were again surprised on 26 November when 300,000 Communist
Chinese forces entered the war. UN forces began a continuous withdrawal
and retreat that lasted for the rest of 1950, finally halting some 70
miles south of Seoul.5 Once again it was American air power that slowed
the advance of Communist forces. The enemy attack bogged down under the
constant assault by air interdiction missions as well as close air support
by Fifth Air Force, Navy, and Marine forces. UN forces went on the
offensive in late winter and early spring of 1951, recapturing Seoul and
advancing northward.6 Finally, in the summer of 1951, armistice
With the coming of the truce negotiations, UN forces, under US Army
general Matthew B. Ridgway, wanted to keep pressure on the Communists in
order to encourage the negotiations process. However, the American Joint
Chiefs of Staff (JCS) wanted no operations that would either appear to be
offensive in nature or result in high casualties. This attitude was
reflected in a JCS message sent to Ridgway on 11 August 1951 that said,
"If Armistice discussions fail, it is of greatest importance that clear
responsibility for failure rest upon the Communists."7
Air Force leaders, still wanting to show just what air power could achieve
in war, were quick to offer interdiction as the solution. Brig Gen Edward
J. Timberlake, Fifth Air Force vice commander and later acting commander,
suggested a road/truck interdiction effort, which was supported by FEAF
headquarters with a goal of paralyzing the Communist transportation system
between the 39th parallel and the front lines.8 The official objective of
Operation Strangle, according to FEAF, was to "interfere with and disrupt
the enemy's lines of communications to such an extent that he will be
unable to contain a determined offensive by friendly forces or be unable
to mount a sustained major offensive himself."9 According to noted air
power historian Robert F. Futrell, both the Air Force chief of staff, Gen
Hoyt S. Vandenberg, and FEAF commander, Gen Otto P. Weyland, had
misgivings about the operation under the conditions imposed by the JCS and
the truce negotiations.10 However, there is no indication that they
expressed those doubts at the time.
General Weyland said the goal was to isolate the enemy, making him unable
to sustain his frontline forces, but then he waffled in this by adding
that a parallel objective was to "punish the enemy to the maximum extent
possible."11 Choosing the name Strangle for the initial road/truck
interdiction operation further confused the issue of just what the
objective was intended to be. Air Force leaders were looking for a strong
name for the operation and wanted to avoid using the term interdiction in
favor of terms that clearly indicated that this was an air campaign.12
Ground commanders seem to have chosen to interpret the term Strangle to
indicate that air interdiction would "strangle" the enemy by choking off
his supplies and preventing him from maintaining an army in the field. The
choice of the name Strangle itself has become a classic lesson in the
dangers of picking names for military operations (see sidebar). The
ultimate result was an unclear objective, loosely interpreted to suit the
goals and needs of various organizations, with no common understanding of
what it was supposed to achieve. The principle of the objective was
clearly violated. Because of this violation, only mixed results came from
the effort. The road/truck interdiction program was short-lived and not
very successful; it killed trucks without really achieving any strategic
objectives.13 Because of the problems with the road/truck interdiction
effort, Eighth Army and Fifth Air Force began a joint survey in July 1951
to consider potential weaknesses in the enemy logistical system. This
survey was to be the basis of planning for the Rail Interdiction Program,
also known as Operation Strangle, even though the survey was not completed
until more than a month after the program began. Unfortunately, another
important lesson flowed from failure. The development of a joint survey
was the correct action to take in planning an air campaign to support
Operation Strangle's perceived objectives. But surveys should be completed
and the right questions asked before the campaign begins. The joint study
focused on the logistics needs of the Communist field armies and
determined that the enemy required 2,400 tons of supplies daily to support
their combat forces. Further analysis indicated that while it would take
approximately 6,000 trucks to support this effort, 120 railcars could
carry the same load, making rail transport a more reasonable target for UN
air forces to attack. Three alternative solutions were postulated as
potential methods for attacking the rail transport system. Bridges could
be destroyed, rolling stock could be attacked, or the rail lines
themselves could be destroyed. Headquarters FEAF and Fifth Air Force
decided by process of elimination to attack the rail lines as the primary
target, reinforced by secondary attacks on the bridges, as well as
preplanned and target-of-opportunity attacks on rolling stock.14 Here
again, failure to follow through with proper analysis diluted the
effective planning that had previously been done.
The major effort to analyze the enemy logistical system was a textbook
example of how to determine a center of gravity for enemy activity. Rail
transport was indeed essential to the enemy effort in the field. In fact,
Lt Gen Nam Il, the chief Communist delegate to the peace negotiations,
speaking of the overall air effort during the Korean War, attributed the
success of the UN forces to their bombing campaigns.15 But at the same
time, the analysis failed to consider just how successful interdiction
could be in defeating the North Korean rail supply effort. Little
consideration was given to the notion that interdiction is most effective
when combined with a ground campaign which causes the enemy to exhaust his
supplies at a rate that cannot be sustained.
The most successful period for Operation Strangle was the first three
months of the campaign, when Eighth Army was still conducting ground
operations to consolidate and secure its positions. By the autumn of 1951,
when ground activity decreased, so did the effectiveness of the
interdiction effort. While the study had determined the level of supply
effort needed by the enemy when engaged in battle, little consideration
had been given to what level of supply was required to sustain the enemy
in static defensive positions when neither side was conducting offensive
operations. Still less effort was given to considering if the rail
interdiction efforts of Operation Strangle could reduce the enemy supplies
reaching the front to a level below that needed to sustain a static
defense. Air planners and air commanders had simply assumed through their
beliefs in air power that they could interdict the enemy supply levels to
the point where the enemy would be forced to negotiate a settlement
rapidly and in good faith.
In its official pre-Rail Interdiction Program estimate of 14 August 1951,
Fifth Air Force stated that it, FEAF Bomber Command, and naval Task Force
77 together "have the capacity of destroying the enemy's rail system in
North Korea and of hindering his highway transportation system to such an
extent that he will not be capable of opposing the US Eighth Army
effectively."16 In November, when General Vandenberg received an update
briefing at Fifth Air Force headquarters, the assumption that rail traffic
could be reduced to near zero was still held: "Our plan is to reduce the
lines to such a state of unserviceability that we can keep them blocked
with a minimum of effort."17 This estimate was given despite the fact that
at the time a maximum effort was not achieving the same objective.
The difficulty of cutting rail traffic was not fully considered. Planners
simply asserted that air attacks could make sufficient cuts in rail lines
to stem the flow of supplies. This assumption ignored the recent
experiences of IX Tactical Air Command (TAC) rail interdiction efforts in
World War II, which showed that cutting rail lines was extremely difficult
and that, until a new munition was developed, this was not a particularly
effective technique when compared with the effort involved in achieving
those cuts.18 The failure to follow through with the analysis process to
determine if effective means of interdicting the rail supply effort below
acceptable levels for the enemy was a major defect in the planning effort.
Planners asked the right questions when they determined rail transport as
a center of gravity. But they neglected to ask the logical follow-up
questions to determine if the center of gravity could successfully be
defeated with the means at hand. During its most successful period,
Operation Strangle decreased enemy rail transport to between 4 or 5
percent of its prewar levels. However, that 4 or 5 percent, combined with
other methods of transport, was sufficient to support the needs of the
Communist forces in a static defensive position.19
In fact, making cuts in rail lines was extremely difficult. Only one out
of every four sorties flown actually produced a rail cut. With a typical
sortie carrying two 500-pound bombs, the statistical results showed only
12.9 percent of the ordnance dropped had any effect on the rail system.20
As Operation Strangle entered the Korean winter, the results were even
worse. Bombs often simply skipped off the frozen ground and exploded
harmlessly, littering the countryside with shrapnel but not cutting the
rail lines. In addition, by this time Communist forces had begun to react
to UN air attacks, decreasing the effect of successful bombing missions
and increasing the danger to UN flyers.
Not accounting for enemy reaction to Operation Strangle was another key
lapse in the planning proccess. Initially, the interdiction effort had
been successful, destroying enemy supplies faster than they could be
replaced. Combined with Eighth Army ground activity, the rail interdiction
effort was hurting the enemy. There were even reports of food shortages in
some areas. Realizing the need to maintain their supply lines, the
Communists cannibalized existing double-track rail lines in order to
assure that at least a single-track rail line would remain open. In many
cases, trains were shuttled the short distances between rail cuts and the
cargo unloaded and transferred to another existing rail line in order to
complete the journey to the front. By October 1951, it seemed as if the
rail interdiction effort would prove successful. But the enemy was
beginning to overcome the difficulties created by the interdiction effort
and FEAF proved slow to react to enemy tactical changes, signaling the
eventual downfall of Operation Strangle.
The first enemy reaction was to increase the air defense pressure on FEAF
Bomber Command attacks on the bridge system. The slow-moving B-29s were
extremely vulnerable to MiG activity, and with only a limited number of
B-29s available, high loss rates could not be tolerated. Communist air
attacks against Bomber Command formations intensified until restrictions
were placed on how far north they could operate.
The enemy proved extremely capable as well in the area of deception
techniques, creating the impression of destroyed bridges and rail lines
when, in fact, the bridges or rail sections were in good working order.
Bypass bridges were rapidly constructed, in some cases even before the
original bridge was destroyed. In addition, some bridges had removable
sections so that they appeared to be destroyed by day but were fully
functional for nightly rail traffic.21 A poor understanding of deception
techniques was a serious weakness in FEAF intelligence and photo analysis
efforts. It resulted in a failure to strike numerous targets that should
have been hit and allowed the enemy to successfully move his supplies
while the UN forces believed they had stemmed that movement.
The enemy proved to be willing to commit a vast amount of human resources
to the effort of keeping rail lines open. Manpower, in the form of
enforced Korean and Chinese labor, was a virtually unlimited resource that
could be stationed at close intervals along the rail lines. When rail cuts
were made, they could be repaired in very short periods of time, often in
no more than six to eight hours and sometimes less.22 The tools and
supplies required were simple, plentiful, and inexpensive. The end result
was that, typically, a rail line that was cut by air attacks was back in
operation by the next day and had to be continually restruck to keep it
shut down. The cost to the UN forces in materiel resources was far greater
than to the enemy. This same lack of understanding of what reliance on
human labor and simple tools could accomplish would haunt US forces again
during the Vietnam War. Being technologically oriented, the US
military--and perhaps especially the Air Force--gave short shrift to
nontechnical solutions to military problems.
Another way Communist forces used their vast manpower resources to good
advantage was the simple expedient of human transportation. An April 1952
study of enemy reactions to the Rail Interdiction Program showed, for
example, that 100 men transporting mortar shells on their backs could meet
the enemy's daily requirement for mortar shells for an indefinite length
of time. By combining those supplies reaching the front by rail, truck,
and foot, Communist forces were not only meeting their needs, they were
actually able to stockpile some supplies for future use.23 In spite of a
maximum, sustained effort by air forces, interdiction alone could not meet
the objectives set for Operation Strangle. Lack of analysis combined with
enemy ingenuity and perseverance to stifle the air interdiction effort.
The enemy understood their logistical problems far better than UN analysts
did. By using the blinders of Western thinking to view possible solutions
to the problems of logistical support while under air attack, UN forces
ignored the possibility of simple, but labor-intensive, alternatives.
The most critical enemy reaction to the interdiction effort was the
movement of antiaircraft assets to protect the rail network. FEAF viewed
this as proof that the Communists needed the rail system and that the air
attacks were hurting them. In this assessment they may have been correct.
But the enemy's ability to sustain attacks was significantly greater than
FEAF's ability to sustain the increasingly greater losses of aircraft and
personnel in making those attacks. Fifth Air Force units were assigned
specific sections of rail lines to attack. Because the same sections of
railway were attacked day after day, often in the same sequence of
sections and at the same time of day, the Communists could concentrate
automatic weapons fire and antiaircraft artillery (AAA) along the rail
line to provide the best air defense.24 Because of the concentrated AAA
fire, bombs had to be dropped from higher altitudes, decreasing their
acuracy. In addition, a larger percentage of the sorties had to be devoted
to suppression of enemy air defenses, further decreasing the effectiveness
of attempts to cut the rail network.
In the end, the cost became prohibitive for UN air resources. In the
seven-month period from the start of the Rail Interdiction Program until
mid-March 1952, 243 aircraft were lost on interdiction missions and
another 290 suffered major damage. The cost in human terms was 245 airmen
killed or missing and 34 wounded. The loss rate was double the replacement
rate for aircraft, four times the rate when seriously damaged aircraft are
included.25 Obviously, this kind of negative exchange rate could not be
sustained. The cost was simply too great, especially when compared to the
damage being inflicted on the enemy.
Failure to account for enemy reaction to air attacks and failure to
adequately adjust tactics to deal with enemy reactions proved to be
another costly error for Operation Strangle. Originally designed to last
45 days, the campaign was continuously extended as it struggled to meet
its ill-defined objectives. UN military planners saw no obvious
alternative course of action to achieve the objectives either of
"strangling" enemy logistics or of pressuring the enemy to negotiate in
good faith. So the Rail Interdiction Program was simply extended.
Continuing the campaign long beyond its intended length without careful
consideration of the costs only further separated Operation Strangle from
its originally envisioned objectives, no matter which definition of the
objectives was used. By December 1951, Fifth Air Force had concluded that
Operation Strangle was not working, but General Ridgway insisted it should
That General Ridgway should insist on continuing an air operation that his
air component considered futile further points out a problem in the air
campaign planning process used in Korea. General Ridgway inherited the
Korean command structure from General MacArthur, albeit with some
modifications. It remained throughout the war an Army command structure
masquerading as a unified command system. But it was never a truly unified
command structure with equivalent-level component commanders, each
representing and controlling his own area of expertise. This was
especially true for air activity. Even within the Air Force, no single
commander or staff organization had control over all air assets. Fifth Air
Force controlled fighter-bomber and light bomber assets, and FEAF Bomber
Command controlled B-29 attacks. Meanwhile, naval Task Force 77 controlled
naval air assets, and the 1st Marine Air Wing worked independently as
well. Eventually a geographical area of responsibility agreement was
worked out giving Marine, Navy, and Air Force units separate areas of
operations.27 The beginnings of the route pack system used in Vietnam can
be seen in these service-oriented geographical arrangements.There was no
air component commander and little or no coordination between the
services, significantly diminishing the overall effectiveness of air
In the end, interdiction failed to achieve the results its early planners
had envisioned, and it became a matter of putting the best face on an
unsuccessful operation. General Ridgway told the JCS that air interdiction
had seriously affected enemy supply operations, diverted thousands of
troops, and destroyed thousands of trucks and rail cars.28 The Air Force
proudly cited the statistics showing the destruction they had wrought. But
the FEAF staff study that would end the Rail Interdiction Program
concluded that interdiction of rail lines was not worth the effort and
that--given the restrictions placed upon them in terms of unclear
objectives, lack of effective munitions, and geographical restrictions
along the northern border of Korea--air power could not be decisive in
Failure to clearly state objectives after considering accepted doctrine,
and to thoroughly analyze enemy centers of gravity and the available means
of attacking those centers, had doomed Operation Strangle before the first
sortie ever left the ground. Lack of thorough planning and lack of a
unified command structure with control over all air assets had further
weakened the efforts of Operation Strangle. Attempting to simply extend a
short-term operation into a full aerial campaign would not suffice in
achieving the objectives. Slow reaction to enemy efforts to defeat
Operation Strangle depleted resources until it was finally admitted that
the effort was insufficient.
Air interdiction had been successful in limited roles earlier in the
Korean War. But it must be remembered that those efforts were for a period
of limited duration and in coordinated effort with ground operations to
achieve maximum pressure on enemy resources. Planners of military
operations, especially air planners, should consider the legacy of
Operation Strangle before planning future air campaigns.
1. Larry H. Addington, The Patterns of War Since the Eighteenth Century
(Bloomington, Ind.: Indiana University Press, 1984), 253-56.
2. Secretary of the Air Force, Office of Public Affairs, Korea: . . . The
Suspended War (Kelly AFB, Tex.: Office of Public Affairs, 1990), 1.
3. Ibid., 2. USAF fighters downed seven North Korean aircraft that day,
including the first kills by USAF jet aircraft.
4. Addington, 256-57.
5. Ibid., 257.
6. Ibid., 258.
7. Message, 98713, Joint Chiefs of Staff to CINCFE, 11 August 1951.
8. Robert F. Futrell, The United States Air Force in Korea, 1950-1953 (New
York: Duell, Sloan and Pearce, 1961), 296.
9. Robert F. Futrell, Air Operations in the Korean War, 1950-1953
(Washington, D.C.: USAF Historical Research Division Liaison Office, March
10. Futrell, USAF in Korea, 403.
11. Otto P. Weyland, "The Air Campaign in Korea," Air University Quarterly
Review 6, no. 3 (Fall 1953): 21.
12. History, Fifth Air Force, July-December 1951, appendix, "Notes on the
Use of the Term `Operation Strangle'," 2.
13. Col R. L. Randolph and Lt Col B. I. Mayo, The Application of FEAF
Effort in Korea, FEAF Deputy Commander for Operations, staff study, 12
April 1952, 5.
14. Futrell, USAF in Korea, 403-5.
15. Research Studies Institute, United States Air Force Operations in the
Korean Conflict, 1 November 1950-30 June 1952 (Maxwell AFB, Ala.: Air
University, 1955), 138 (hereafter cited as RSI study).
16. "The Story of `Operation Strangle'," Air Intelligence Digest, January
17. Ibid., 10.
18. RSI study, 138.
19. Futrell, USAF in Korea, 436.
20. Ibid., 409.
21. Maj Felix Kozaczka, "Enemy Bridging Techniques in Korea," Air
University Quarterly Review 5, no. 4 (Winter 1952-1953): 59.
22. RSI study, 150.
23. Randolph and Mayo, 5.
24. Futrell, USAF in Korea, 408.
25. Randolph and Mayo, 3.
26. Futrell, Air Operations in Korea, 26.
27. Futrell, USAF in Korea, 296.
28. RSI study, 152.
29. Randolph and Mayo, 14.
Lt Col Michael A. Kirtland (BA, Coe College; MPA, University of Colorado)
is a military doctrine analyst at the Airpower Research Institute, Center
for Aerospace Doctrine, Research, and Education, Maxwell AFB, Alabama. He
was a member of the initial cadre in the development and deployment of
ground launch cruise missiles, serving at the training squadron and as
chief of training at Florennes, Belgium. He served as a military studies
instructor at the US Air Force Academy and as a Titan II missile launch
officer. He was the first associate editor of the Airpower Journal and
haas published in numerous military publications. He complied and edited
the Air University Review Index and is currently completing the editing of
the five-year index of Airpower Journal. Colonel Kirtland is a graduate of
Squadron Officer School, Air Command and Staff College, Air War College,
and the National Security Management Program.
The conclusions and opinions expressed in this document are those of the
author cultivated in the freedom of expression, academic environment of
Air University. They do not reflect the official position of the U.S.
Government, Department of Defense, the United States Air Force or the Air
Ed Evanhoe, PO Box 916, Antlers, OK, 74523-0916
Life Member: Special Forces & Special Operations Associations
Author: DARKMOON: Eighth Army Special Operations in the Korean War