 He was involved in the negotiations which led to the Tripartite Pact, which conversely he was vocally opposed to.He was also an early proponent of the use of radar technology, and severely criticized Admiral Shigeyoshi Inoue and other members of the senior naval staff for their "old-fashioned thinking" and inability to grasp the importance of the new technology.On 6 October 1941, Yanagimoto was given command of the aircraft carrier , on which he participated in the attack on Pearl Harbor in the opening stages of the Pacific War.