Foreign Relations of the United States, 1950, Korea, Volume VII

795.00/8–1850

Memorandum Prepared in the Central Intelligence Agency

secret

Washington, August 18, 1950.¹

Subject: Factors Affecting the Desirability of a UN Military Conquest of all of Korea

Conclusions

Although an invasion of North Korea by UN forces could, if successful, bring several important advantages to the US, it appears at present that grave risks would be involved in such a course of action. The military success of the operation is by no means assured because the US cannot count on the cooperation of all the non-Communist UN members and might also become involved in hostilities with Chinese Communist and Soviet troops. Under such circumstances there would, moreover, be grave risk of general war.

Discussion

A successful invasion of North Korea by UN armed forces could bring several important advantages:

1. The conquest of North Korea by UN forces would represent a major diplomatic defeat for the USSR. It would have a profound effect on the entire non-Communist world and would give renewed hope to anti-Communists in both the European and the Asian Satellite states. The recovery of a Satellite from Soviet domination, regardless of its geographical position or political importance, would be a decisive victory for the Western world.

2. The military victory achieved by the UN forces would greatly increase the prestige of the UN and particularly would bring prestige to the US as the chief participant in the UN forces. The countries of Western Europe and the Near East would place greater reliance in the UN as a practical force for world peace and in the determination and ability of the US to stem Communist aggression.

3. UN military conquest of Korea would not only deny the USSR a strategic outpost from which to threaten Japan, but it would provide the Western Powers with a buffer area and a wedge into Communist held territory.…

4. The elimination of the arbitrary division of Korea at the 38th parallel and the expulsion of the North Korean regime would appear to provide an opportunity to bring about the economic and political unification of the country. Korean unity would be in accord with the wishes of the Korean people, the announced policy of the US, and the recommendations of the UN.

In addition to these advantages, however, an invasion of North Korea would involve certain grave risks for the US:

1. It is doubtful whether the US could secure the support of its allies and of other non-Soviet nations in the UN for such a course of action. Many non-Communist members of the UN would almost certainly be opposed to any action which would involve the risk of strong counteraction by the USSR. The nations participating with the US in Korea do not wish to become deeply involved in Korea or to take action which might bring them nearer to a general war. They would probably take the position that the UN forces are not committed to the liberation of North Korea and that the SC’s resolutions do not provide an adequate legal basis for the conquest. Consequently, US action would provide the USSR with a strong wedge for attempting to separate the US from its Western European allies. It would also have serious repercussions among Asian nations, particularly India, which is habitually distrustful of Western motives, and might convince many Asians that the US is, after all, an aggressive nation pursuing a policy of self-interest in Asia.

2. The invading forces might become involved in hostilities with the Chinese Communists. As it became apparent that the North Koreans were being defeated in South Korea, the Chinese might well take up defensive positions north of the 38th parallel. The USSR, which might welcome the outbreak of hostilities between the US and China, would thus have an additional opportunity of driving the wedge more deeply between the US and its allies. The USSR might use Chinese Communist troops at any stage in the fighting, but their participation would be especially useful at the 38th parallel where UN members could legally discontinue their support of the US policy.

3. Inasmuch as the USSR would regard the invasion of North Korea as a strategic threat to the security of the Soviet Far East, the invading forces might become involved, either directly or indirectly, in hostilities with Soviet forces. The USSR is now in a high state of readiness for general hostilities, and the Kremlin might well calculate that, with US mobilization set in motion, the USSR is better prepared now than it would be later for a full-fledged test of strength with the US. It could therefore place Soviet forces on the 38th parallel and oblige the US to initiate hostilities against Soviet forces under conditions which would alienate most of Asia from the US–UN cause in Korea, permit full exploitation of the propaganda theme that the South Koreans under US guidance opened the aggression against the North Koreans and other peace-loving peoples, and enable the USSR to neutralize and conquer most of Europe and the Near East before the impact of US industrial mobilization could be felt upon the defensive capability of those areas.

Even if the USSR should not choose to utilize a UN attempt to conquer North Korea as a pretext for the inauguration of general hostilities against the west, it is probable that the Kremlin would be prepared by one method or another to prevent UN occupation of North Korea. Along with exploiting fully its veto power in the UN and the opportunity for charging the US with aggressive action, the USSR might well provide sufficient ground, air, or naval assistance to interdict UN communications, halt the ground advance, and neutralize UN air and naval superiority. Concurrent with such action, the USSR might well inaugurate new limited aggressions elsewhere in order to offset the advantages which might be gained by an advance into North Korea and to strain further UN military capabilities. There is no assurance that the USSR is unprepared to assume such risks.

4. The conquest of North Korea would not provide assurance of peace throughout the country or of true unification. The Soviet high command would almost certainly attempt to withdraw into Manchuria or into the USSR a large portion of the North Korean forces. From these areas the USSR might continue to threaten aggression and infiltration and thus produce such instability as to require the continuing presence of large numbers of US or UN forces. Moreover, Syngman Rhee and his regime are unpopular among many—if not a majority—of non-Communist Koreans. To re-establish his regime and extend its authority and its base of popular support to all of Korea would be difficult, if not impossible. Even if this could be done, the regime would be so unstable as to require continuing US or UN military and economic support. If, as one alternative, a new government should be formed consequent to a UN-supervised free election, there is no assurance that the Communists would not win either control of or a powerful voice in such a government. If, as another alternative, a prolonged trusteeship under UN control and with US participation were established, instability would, nevertheless continue, with probably even the non-Communist Koreans reacting against the substitution of outside control for independence. Furthermore, Korea once more would become the catspaw of international politics, and its ultimate status would be dependent upon the comparative strength and ambitions of the countries whose representatives supervised the trust administration.

1. The source text indicated that this was the date on which this document was received in the NSC.