<P> The official Instrument of Surrender was signed on September 2, and the United States subsequently occupied Japan in its entirety . </P> <P> At the end of the Second World War, Japan was occupied by the Allied Powers, led by the United States with contributions from Australia, the United Kingdom and New Zealand . This was the first time since the unification of Japan that the island nation had been occupied by a foreign power . The San Francisco Peace Treaty, signed on September 8, 1951, marked the end of the Allied occupation, and when it went into effect on April 28, 1952, Japan was once again an independent state, and an ally of the United States . </P> <P> In the years after World War II, Japan's relations with the United States were placed on an equal footing for the first time at the end of the occupation by the Allied forces in April 1952 . This equality, the legal basis of which was laid down in the peace treaty signed by forty - eight Allied nations and Japan, was initially largely nominal . A favorable Japanese balance of payments with the United States was achieved in 1954, mainly as a result of United States military and aid spending in Japan . </P> <P> The Japanese people's feeling of dependence lessened gradually as the disastrous results of World War II subsided into the background and trade with the United States expanded . Self - confidence grew as the country applied its resources and organizational skill to regaining economic health . This situation gave rise to a general desire for greater independence from United States influence . During the 1950s and 1960s, this feeling was especially evident in the Japanese attitude toward United States military bases on the four main islands of Japan and in Okinawa Prefecture, occupying the southern two - thirds of the Ryukyu Islands . </P>

When did japan and the us become allies