Foreign Relations of the United States, 1952–1954, Korea, Volume XV, Part 1

INR-NIE files

Special National Intelligence Estimate¹

top secret
SE-25

Washington, April 28, 1952.

Military Indications of a Possible Large-Scale Communist Attack in Korea in the Immediate Future²

the problem

To estimate, on the basis of military indications, Communist intentions with regard to a large-scale military attack in Korea in the immediate future.

conclusions

1. There has been a general strengthening of Communist military capabilities in Korea since the beginning of the armistice negotiations. The enemy is credited with a greater offensive potential than he had previously enjoyed and is believed capable of launching a major ground attack with little warning, and air attacks which initially could be of substantial proportions.

2. In recent weeks there has been increased enemy activity in Korea. There have also been reports, partly unconfirmed, of aggressive enemy intentions. These activities and reports do not constitute acceptable indications of a Communist intent to initiate large-scale offensive action in the immediate future. Nevertheless, the increased military activity in Korea and the general situation in Korea may represent preparations taken in anticipation of a political decision either:

a. To launch a limited offensive, with little or no warning; or

b. To undertake a large-scale offensive.

discussion

Communist Capabilities in Korea

3. During the armistice negotiations, the Communists have substantially increased their capabilities in Korea. They have replaced their losses, re-equipped their units, retrained their troops, and reorganized and redisposed their forces. They have built up their ground forces from an estimated 502,000 to the present estimate of 866,000 personnel. Qualitative improvement has accompanied the quantitative build-up; they have made significant additions of armor and artillery and have substantially increased the fire power of all units. (A detailed chart of build-up since July 1951 is attached hereto as Annex “A.”)³

4. The Communists have made excellent use of the long period of fairly static operations to improve their logistical position. As a result the supply position of the Communists in forward areas, despite continued air and naval attacks by UN forces, is far better than at any time since the Chinese Communist intervention in Korea.

5. The enemy ground forces in Korea could launch a major attack with little warning. It is estimated that the Communists have the logistic capability to maintain the momentum of a major offensive for from 5 to 10 days. Difficulties in connection with the movement of supplies from forward dumps to the attacking units would be the limiting factor.

6. The capabilities of the Communist Air Force in the Korean area (North Korea, Manchuria, and Northeast China) have improved steadily and rapidly. During the armistice negotiations, the estimated Communist combat aircraft strength in the Korean area has increased from 500 aircraft to the present total of 1,250 aircraft plus 75 transports, including an increase from 450 jet fighters to the current 800. There are also 400 combat aircraft deployed in south and central China which could not be committed in Korea without redeployment. There is a sufficient number of operational airfields in Manchuria from which attacks by the above aircraft could be launched against UN forces. An apparently effective system of air control and warning is believed operating in North Korea. Communist pilots in Manchuria have been engaged in an intensive training program. The Communists have also demonstrated a significant capability to support logistically a sizeable air force in Manchuria.

7. The Communist Air Force in the Korean area could launch an air attack which might inflict substantial damage upon United Nations ground forces, naval and air installations, and lines of communications in Korea. Initially, a force of approximately 500 MIG–15’s, 150 pistonengined fighters and 150 light bombers could be made available, but without unusual success in countering UN efforts against this attack, it is believed it could not be sustained.

Indications of Communist Military Intentions in Korea

Ground

8. In recent weeks there have been several indications, generally unconfirmed, of increased enemy activity in Korea.

a. The movement of two Chinese Communist armies, one forward towards the western sector and one eastward towards the central sector, has been accepted. The movement of three other CCF armies toward the western sector has been reported but is unconfirmed.

b. Reports of PW’s and other information point to the possibility of a forward movement of some armored vehicles from the Wonson area on the east coast. Elements of the 1st and 3rd Armored Divisions are accepted as attached to or in direct support of front-line units on the west and west central fronts. Other elements of these two divisions remain unlocated. During the past several months unconfirmed reports have also referred to the southward movement of the North Korea V Corps.

9. During the past few weeks there have been four PW reports of a new offensive. Most PW’s, however, have continued to refer to enemy defensive plans, including the strengthening of defense fortifications and the rotation of front-line units.

10. The possibility that the enemy is preparing to relieve some frontline units is further suggested by PW reports that the CCF 67th Army will relieve the 68th Army and that the CCF 26th Army is to be relieved in the immediate future. There is no confirmation, however, that the relief of any front-line units is under way.

11. There has been one recent report that North Korean guerrilla forces are being trained to infiltrate UN lines (a tactic which has preceded previous offensives). This report receives some substantiation from the recent capture by UN forces of a small number of line-crossers.

Air

12. The most significant recent incident with respect to enemy air activity was a visual sighting on 13 April of 450 jet aircraft on Tatungku airfield and 50 on Antung airfield. This is approximately twice the number of aircraft ever before sighted on these airfields and very nearly the total estimated MIG–15 strength in Manchuria. Although an error of up to 75 aircraft in this sighting is possible, this report is regarded as substantially accurate. Subsequent observations during the day disclosed that this total has been reduced to approximately 200 aircraft on both fields. Possible explanations for this concentration are that bad weather precluded the use of other Manchurian airfields or that this was a test of personnel and facilities under crowded conditions. It is also possible that this represented a “show of force” designed to influence the armistice discussions.

13. Other indications that the enemy may be preparing for increased air activity, possibly including operations over South Korea on a large scale, were: (a) the reported observation on 1 April of a MIG–15 over the Seoul–Suwon area on what appeared to be a photo-reconnaissance flight; (b) recent increased willingness of enemy pilots to engage UN aircraft; (c) reported repairs of Pyongyang airfields; and (d) observation of some vehicle activity at Taechon airfield on 13 April, the first observation of activity at any of the three airfields in the Sinanju area in some time.

1. Special National Intelligence Estimates (SNIE’s) were high-level interdepartmental reports presenting authoritative appraisals of vital foreign policy problems on an immediate or crisis basis. SNIE’s were drafted by officers from those agencies represented on the Intelligence Advisory Committee (IAC), discussed and revised by interdepartmental working groups coordinated by the Office of National Estimates of the CIA, approved by the IAC, and circulated under the aegis of the CIA to the President, appropriate officers of cabinet level, and the National Security Council. The Department of State provided all political and some economic sections of the SNIE’s.
2. According to a note on the cover sheet, the intelligence organizations of the Department of State, the Army, the Navy, the Air Force, and the Joint Staff participated with the Central Intelligence Agency in the preparation of this estimate. All members of the Intelligence Advisory Committee concurred in this estimate on Apr. 24, 1952.
3. Not printed; it is a chart comparing Chinese Communist forces and North Korean Army strength in July 1951 and April 1952.