Kyūma served as the Director General of the Japan Defense Agency from 1996 to 1998 under then Prime Minister Ryutaro Hashimoto.

He later had to withdraw his remarks, admitting that the Japanese "Cabinet officially adopted a unified view supporting the U.S.-led war.

[7] In January 2007 he criticized the United States over not getting the approval of Okinawa's governor during efforts to relocate the Marine Corps Air Station Futenma.

[8] Kyūma resigned as Defense Minister on 3 July 2007 for remarks made at Reitaku University in Kashiwa, Chiba Prefecture on 30 June.

In this speech, he stated "I now have come to accept in my mind that in order to end the war, it could not be helped that an atomic bomb was dropped on Nagasaki and that countless numbers of people suffered great tragedy."