795.00/10–350
Memorandum by the Deputy Director of the Office of Northeast Asian Affairs (Johnson) to the Assistant Secretary of State for Far Eastern Affairs (Rusk)
Subject: Threat of Chinese Intervention in Korean Conflict.
Reference London’s 1934 of October 3. Although the statement attributed to Chou En-lai undoubtedly contains a large element of bluff directed at forestalling decisive action on the UK resolution on Korea, I do not feel that we can assume it is entirely bluff.
For reasons which are not clear, unfortunately General Mac Arthur has not thus far committed across the 38th parallel any UN forces. If he had done so, the position vis-à-vis the Chinese would be much stronger. It appears that he may be testing ROK forces north of 38 with the thought that it might not be militarily necessary to commit UN forces north of the 38th. We are not openly committed to the use of UN forces across the 38th and it may, therefore, be well worthwhile further to explore the possibility of using entirely ROK forces for the subjugation of North Korea, of course, continuing our present logistic and tactical Air and Naval support, thus maintaining the UN umbrella. This would maintain the UN umbrella over the operation while reducing the grave risk of calling the Chinese bluff. Although this would extend de facto ROK control over North Korea, I do not think we would encounter serious difficulty in restraining Rhee from extending de jure control until the UN machinery had operated. While occupation by exclusively ROK units would be much more sanguinary than we had hoped, the UN Commission and American advisors attached to the ROK units should be able to exercise some restraining influence. This also has the added advantage of avoiding the great complexities of carrying out genuine UN occupation of North Korea.
I suggest that you recommend to Mr. Matthews that we immediately request Defense to ascertain (1) what General Mac Arthur’s present intentions are with regard to the use of UN forces north of 38 and (2) his assessment of the capabilities of ROK troops to carry out this operation.