Koiso, a reserve General with experience in intelligence but not in combat, was appointed Prime Minister after the resignation of TOJO in July 1944. He was to share power with Admiral Yonai (Navy Minister and Assistant Prime Minister) who was associated with KONOYE, KIDO and the Emperor HIROHITO, and therefore with the peace faction. Koiso was never more than an unstable interim leader, having the support of neither the peace faction nor the militarists, and therefore having no influence on the prosecution of the war or on the preparations for peace. He believed Japan could not win the war but felt the US would not give acceptable terms. In this position he presided over defeat after defeat. He had publicly committed his government to victory in Leyte in a radio broadcast on 8 November 1944. The December decision to abandon Leyte, followed by the defeat at Iwo Jima, brought his government near collapse.
Koiso was ignored by the military and not involved in decision-making. When the Americans landed on Okinawa, Koiso demanded that the military structure be reorganized so that he, the Prime Minister, would be consulted. When the Admirals and Generals refused, Koiso resigned in April 1945 and he was succeeded by SUZUKI.