日ソ中立条約
The Soviet Union and Japan maintained a fairly scrupulous neutrality toward each other after signing the Soviet–Japanese Neutrality Pact on 13 April 1941, although the two countries were allied with each other′s World War II enemies from 1941 until the conclusion of the war in 1945. The Soviet Union turned down Allied requests for any actions which might provoke Japan, but discussed plans to base American aircraft on Soviet territory for operations against Japan after the Soviet Union had declared war on Japan.