Yonaguni is the last inhabited island at the southwestern end of Japan’s Nansei chain, about 110 kilometers from Taiwan. It is scheduled to host a U.S. Marine Corps anti-ship missile launcher for the first time during Exercise Keen Sword, which runs Oct. 19-29, 2026. The Okinawa-based 12th Marine Littoral Regiment plans to bring both its Navy-Marine Expeditionary Ship Interdiction System (NMESIS) and its Marine Air Defense Integrated System (MADIS) to the island.
The plan was made public by Yonaguni’s local government, after the Okinawa Defense Bureau relayed the deployment plans on Oct. 1, 2026. It puts the Marines’ ground-based anti-ship launcher on Japan’s southwesternmost island for the length of the exercise.
Defense News reported the deployment on Oct. 5, 2026, in a report by Leilani Chavez drawing on Japanese defense officials and the island’s government. “The systems will be deployed to Yonaguni for the first time,” the report states, describing NMESIS as the anti-ship system and MADIS as the air-defense system.
What NMESIS is
NMESIS puts a ship-killing missile on a truck with no one in the cab. When the Marine Corps released the first image of the system in April 2021, USNI News reported that the service had “mounted a Raytheon Naval Strike Missile on a modified unmanned Joint Light Tactical Vehicle.” The launcher vehicle is known as the Remotely Operated Ground Unit for Expeditionary (ROGUE) Fires, per the same report, and the program supports the Corps’ modernization priority of “enabling sea control and denial operations.”
Defense News put the system’s reach at around 115 miles.
The 12th Marine Littoral Regiment, part of the 3rd Marine Division, is the unit the NMESIS and MADIS systems first arrived with, in June, according to Defense News. The same units earlier deployed to the Philippines’ Batanes Islands and Laoag province during the Balikatan drills, the report says. Yonaguni would add a Japanese island to that list of NMESIS stops.
Keen Sword 2026
Defense News calls Keen Sword “the largest U.S.-Japan biennial joint drill.” Citing Japan’s Ministry of Defense, the outlet reported that troops from nine countries, including the Australian and French armies, are to join 45,000 Japanese Self-Defense Forces personnel for the Oct. 19-29 exercise.
This year’s drill shifts toward ground-based, multi-island, sea-denial operations, per the report. Other pieces of that picture, as Defense News listed them:
- The U.S. Army is to deploy HIMARS rocket launchers to Camp Ishigaki, about 80 miles from Yonaguni.
- Japan’s Ground Self-Defense Force plans to showcase three missile systems: the Type-25 surface-to-ship missile, the Type-88 and the upgraded Type 03 Chu-SAM Kai. The Type-25, formerly the upgraded Type-12, was fielded across the Nansei Islands in late March, per the report.
- The carrier USS George Washington will not take part.
- The V-22 Osprey will not participate, Yonaguni Mayor Tsuneo Uechi told Mainichi Shimbun on Oct. 2, 2026, according to the report.
Large equipment bound for Yonaguni is to be shipped through Kubura Port, and local authorities have asked residents to avoid roads while it moves, Defense News reported. The island already hosts a Ground Self-Defense Force radar and surveillance site, set up in 2016 to fill what the report calls a “surveillance vacuum” in the waters off the island.
Scheduled, not yet ashore
As reported on Oct. 5, the Yonaguni deployment is tied to the Keen Sword window. Defense News also reported that the local government remains opposed to the exercises and was still in talks with the Ministry of Defense, and that local officials said the exercise had been scaled down from a larger original plan.
If the schedule holds, NMESIS lands on Yonaguni for the Keen Sword window of Oct. 19-29, 2026, the first time the launcher has operated from Japan’s southwesternmost island.
Top image: Marines with the 12th Marine Littoral Regiment maneuver an NMESIS launcher during training on July 6, 2026. Image Credit: Lance Cpl. Sawyer Abbott / U.S. Marine Corps — Public domain / Wikimedia Commons
This article was produced with the assistance of AI and reviewed by Combat Rated editors prior to publication.