the "Sixty Years after Hiroshima" issue of The Weekly Standard, the American historian Richard B. Frank points out that there are a number of schools of thought with varying opinions of what caused the Japanese to surrender. He describes what he calls the "traditionalist" view, which asserts that the Japanese surrendered because the Americans dropped the atomic bombs. He goes on summarize other points of view in conflict with the traditionalist view: namely, that the Japanese government saw their situation as hopeless and was already ready to surrender before the atomic bombs – and that the Soviets went to war against Japan. Tsuyoshi Hasegawa's research has led him to conclude that the atomic bombings were not the principal reason for Japan's capitulation. He argues that Japan's leaders were impacted more by the swift and devastating Soviet victories on the mainland in the week after Joseph Stalin's 8 August declaration of war because the Japanese strategy to protect the home islands was designed to fend off an Allied invasion from the south and left virtually no spare troops to counter a Soviet threat from the north. Furthermore, the Japanese could no longer hope to achieve a negotiated peace with the Allies by using the Soviet Union as a mediator with the Soviet declaration of war. That, according to Hasegawa, amounted to a "strategic bankruptcy" for the Japanese and forced their message of surrender on 15 August 1945. Others with similar views include the Battlefield series documentary, among others, but all, including Hasegawa, state that the surrender was not caused by only one factor or event. The Soviet invasion and occupation of the defunct Manchukuo marked the start of a traumatic period for the more than one million residents of the puppet state who were of Japanese descent. The situation for the Japanese military occupants was clear, but the Japanese colonists who had made Manchukuo their home, particularly those born in Manchukuo, were now stateless and homeless, and the (non-Japanese) Manchurians wanted to be rid of these foreigners. Many residents were killed, and others ended up in Siberian prisons for up to 20 years. Some made their way to the Japanese home islands, where they were also treated as foreigners. Manchuria was "cleansed" by Soviet forces of any potential military resistance. With Soviet support for the spread of communism, Manchuria provided the main base of operations for Mao Zedong's forces, who proved