The aircraft carrier USS Theodore Roosevelt left Yokosuka Naval Base on Monday after a brief port visit and steamed out of Tokyo Bay for Keen Sword, a large scale biennial exercise in and around Japan. The departure put the carrier on course to join a multinational force training to defend Japan.
This year’s exercise began Monday and continues through Oct. 29, bringing together about 56,000 U.S. and Japanese troops along with forces from seven partner nations. The training is designed to test the participants’ ability to defend Japan.
Keen Sword includes drills covering air and missile defense and maritime operations, according to a Monday news release from the exercise’s Combined Joint Information Bureau. Participants will also test troop resupply, casualty evacuation and facilities repair.
The Theodore Roosevelt arrived at Yokosuka on Friday with the guided missile cruiser USS Chosin and guided missile destroyer USS Decatur. The port call included maintenance and resupply before the exercise.
Carrier Strike Group 9 also planned exchanges with Japanese naval counterparts before Keen Sword, according to a Friday news release from the U.S. 7th Fleet. The carrier’s departure followed its brief stay at the home of the 7th Fleet.
Most of the exercise is taking place in western and southern Japan, including the island chain containing Okinawa and stretching from Kyushu to just east of Taiwan. Training areas also include the Sea of Japan, also known as the East Sea, and the East China Sea.
Japan is contributing about 45,000 personnel, 6,100 vehicles, 40 vessels and 260 aircraft, according to a Sept. 29 news release from the Japan Joint Staff. The United States is expected to field approximately 11,000 troops.
The American force includes the Theodore Roosevelt’s strike group, Maj. Ephesian Poinsette, spokesman for Keen Sword, said. The group also includes the guided missile destroyers USS Paul Hamilton and USS Carl M. Levin.
“This is about training how our forces work together,” Poinsette told Stars and Stripes by phone Sunday. “That means sharing information, coordinating decisions, communicating across services and different platforms, and then sustaining those operations.”
Although the exercise rehearses the defense of Japan, it is “not directed at a particular country or a response to a single regional event,” Poinsette said. He described the event as routine and defensive.
“This routine, defensive training exercise builds readiness that makes deterrence credible and preserves peace across the region,” Poinsette said.
Australia, Canada, France, Germany, the Netherlands, New Zealand and the Philippines will participate in Keen Sword. The number of participating partner nations is nearly double the total from 2024, according to the exercise release.
South Korea and the United Kingdom are sending observers, Poinsette said. Their presence expands the international participation surrounding an exercise centered on cooperation between U.S. and Japanese forces.
This year’s Keen Sword will mark the Marine Corps’ first deployment of two of its newest missile systems to Japan’s westernmost island, Yonaguni. Those systems are NMESIS, the Navy-Marine Expeditionary Ship Interdiction System, and MADIS, the Marine Air Defense Integrated System.
About 60 troops from the 12th Marine Littoral Regiment and the U.S. Army will deploy to Yonaguni with the systems. That deployment was listed in a Japanese Defense Ministry planning document posted Oct. 2 on the Okinawa Defense Bureau’s website.
Japan will register another first by deploying its Type-25 surface to ship missile, which previously had been kept at Camp Kengun on Kyushu. Kyushu is the southernmost of Japan’s four main islands.
A Joint Staff spokesman previously told Stars and Stripes that the Type-25 will participate in anti ship training. The missile will not be fired during the exercise.
People gathered to watch the Theodore Roosevelt leave Yokosuka Naval Base on Oct. 19, 2026. Its exit moved the carrier from a short maintenance and resupply stop into a major multinational exercise spanning the air, sea and ground domains around Japan.