 Iwakuni is the only US Marine Corps base on Honshu, the main island of Japan.Iwakuni is home to approximately half of the 1st Marine Aircraft Wing headquartered on Okinawa, elements of the 3rd Marine Logistics Group, and Fleet Air Wing 31 of the Japan Maritime Self Defense Force, according to the command website.In 2017, the base is home to about 15,000 U.S. military and Japanese defense force employees.