740.0011 European War 1939/12389½

Memorandum by the Chief of the Division of Far Eastern Affairs (Hamilton)

The German attack on the Soviet Union will undoubtedly cause much confusion and debate in Government circles in Japan.

Some Japanese Government circles will argue that Russia’s preoccupation with Germany will give Japan freedom for a number of months at least from the menace of a possible Russian attack against Japan and that therefore Japan should embark on military operations against the Dutch East Indies and British Malaya.

Other Government circles in Japan will urge that this is Japan’s opportunity to remove the Russian menace to Japan and that Japan should attack Russia in the Far East. These circles will be supported by those Japanese who fear the setting up by Hitler of a German-dominated régime in the Soviet Far East. I believe that the likely development of Japanese thought will be along this line rather than along the line indicated in the previous paragraph.

If the foregoing analysis is correct, it seems to me that the German attack on Russia is likely to result in a postponement for at least a few months of any Japanese attack upon British and Dutch possessions to the southward.

With regard to the consideration that conclusion by this Government of any agreement or understanding with the Japanese Government would, even though the Japanese Government might not in the long run be able to carry out the provisions of any such agreement, tend to deter Japan for a period of months from embarking upon further aggression southwards, it would seem that such an objective is likely to be realized without the conclusion of any agreement with Japan.

A further consideration now forcefully presents itself: In as much as the fundamental purpose of the proposed agreement with Japan is to maintain and to preserve peace in the entire Pacific area, would an attack by Japan upon Russia be consistent with the spirit and purpose of any such agreement? It seems to me that the answer must be in the negative. It also seems to me that a pledge by Japan not to attack [Page 277] the Soviet Union would be much less likely to be kept by Japan than a pledge by Japan not to attack British and Dutch possessions in the Pacific. In my judgment the strongest motive which would impel Japan not to attack British or Dutch possessions in the Pacific is the likelihood that such action by Japan would result in war with the United States. It seems to me that there is much less likelihood that a Japanese attack on Russia would result in war with the United States and I would therefore be very skeptical of a Japanese pledge not to attack the Soviet Union.

The outbreak of the German-Russian war will probably increase the eagerness of the Japanese Government to conclude with the American Government an agreement of the type under discussion. At the same time the outbreak of the German-Russian war (1) makes less the need on our part for such an agreement, and (2) decreases the chance that Japan would in good faith carry out any pledge made by Japan to pursue courses of peace in the Pacific area (including Far Eastern Russia).

M[axwell] M. H[amilton]

Note: If the policy of the United States develops in the direction of extending substantial aid to the Soviet Union, there may result a situation in which an attack by Japan on Soviet Russia would carry with it substantially more of risk of war with the United States than is in my opinion now the case.