In February 1945, the United States, the United Kingdom and the Soviet Union held a summit conference at Yalta (within the Soviet Union). Based on a request by the United States, they agreed, in utmost secrecy, that the Soviet Union would declare war on Japan within three months of Germany’s surrender. However, after Germany surrendered in May, discord over the post-war handling of Europe raised tensions between the United States and the Soviet Union. The United States began worrying about the increased influence the Soviet Union would gain by joining the war against Japan. Moreover, the United States knew from wireless intercepts and code decryptions that Japan was attempting a peace initiative via the Soviet Union, its partner in a neutrality pact.