<Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> The Pacific War, sometimes called the Asia - Pacific War, was the theater of World War II that was fought in the Pacific and East Asia . It was fought over a vast area that included the Pacific Ocean and islands, the South West Pacific, South - East Asia, and in China (including the 1945 Soviet--Japanese conflict). </P> <P> The Second Sino - Japanese War between the Empire of Japan and the Republic of China had been in progress since 7 July 1937, with hostilities dating back as far as 19 September 1931 with the Japanese invasion of Manchuria . However, it is more widely accepted that the Pacific War itself began on 7 / 8 December 1941, when Japan invaded Thailand and attacked the British possessions of Malaya, Singapore, and Hong Kong as well as the United States military and naval bases in Hawaii, Wake Island, Guam and the Philippines . </P> <P> The Pacific War saw the Allies pitted against the Empire of Japan, the latter briefly aided by Thailand and to a much lesser extent by the Axis allied Nazi Germany and Fascist Italy . The war culminated in the atomic bombings of Hiroshima and Nagasaki, and other large aerial bomb attacks by the United States Army Air Forces, accompanied by the Soviet declaration of war and the Soviet invasion of Manchuria on 9 August 1945, resulting in the Japanese announcement of intent to surrender on 15 August 1945 . The formal surrender of Japan ceremony took place aboard the battleship USS Missouri in Tokyo Bay on 2 September 1945 . Japan's Shinto Emperor was forced to relinquish much of his authority and his divine status through the Shinto Directive in order to pave the way for extensive cultural and political reforms . </P>

When did the us enter japan in ww2