 He also became head of the Investigating Committee for Preparatory Work for Independence (BPUPK), the Japanese-organized committee established as the initial stage of the establishment of independence for the area under the control of the Japanese 16th Army.On 7 September 1944, with the war going badly for the Japanese, Prime Minister Koiso Kuniaki promised independence for Indonesia, although no date was set.This announcement was seen as immense vindication for Sukarno's collaboration with the Japanese.