After World War II, the Supreme Commander of the Allied Powers called upon Ishiwara as a witness for the defense in the International Military Tribunal for the Far East. No charges were ever brought against Ishiwara himself, possibly due to his public opposition to Tōjō, the war in China, and the attack on Pearl Harbor. He displayed his old fire in front of the American prosecutor, arguing that U.S. President Harry S. Truman should be indicted for the mass bombing of Japanese civilians.