Deploying Type-25 and NMESIS to Yonaguni Island for Realistic Defense of the Southwestern Islands in the 2026 Japan-U.S. Joint Exercise

On October 19, the Japan-U.S. joint integrated exercise "Keen Sword 27" began. Approximately 45,000 personnel from Japan and about 12,000 from the U.S., along with participants from seven other countries including France, Germany, the Netherlands, New Zealand, and the Philippines, are involved. This training, which will continue until October 29, is noteworthy not just for the scale of forces but for treating Yonaguni Island as a practical firepower base.

Gathering Anti-Ship Firepower at Yonaguni Island

The Japan Maritime Self-Defense Force has deployed the long-range Type-25 anti-ship guided missile to the island for the first time. Its range is said to be about 1,000 kilometers, potentially reaching the Chinese mainland. However, no launch tests will be conducted this time. The U.S. Marine Corps has also brought the ground-launched anti-ship missile NMESIS and the short-range air defense system MADIS to the island for the first time, while HIMARS will be stationed on the adjacent Ishigaki Island. These deployments are designed to test how quickly a decentralized anti-ship combat network, including sensors, command and control, and logistics, can be established rather than focusing solely on the individual weapon capabilities.

The Focus of Training is After Landing

The exercise includes amphibious operations, air and missile defense, mine clearance, intelligence gathering, logistics, and casualty evacuation. The significance of conducting this on Yonaguni Island, located about 110 kilometers from Taiwan, is clear. The defense of the southwestern islands cannot be achieved merely by placing missiles on the islands. Maintaining sea lines of communication (SLOC), transporting fuel and ammunition, and evacuating damaged units are essential; otherwise, long-range firepower will become fixed targets.

The Chief of Staff of the Japan Joint Staff explained that this training is not aimed at any specific country. However, capabilities and intentions should be considered separately. Regardless of how Beijing perceives it, the mere fact that Japan and the U.S. have demonstrated the ability to place joint firepower at key points along the first island chain changes calculations in times of crisis. The inclusion of defense in the northern maritime area and the supply lines extending from the East China Sea to the Pacific in the same exercise also indicates a shift in viewing the southwestern islands not as isolated territories but as a single operational maritime area.

The Alliance's Weakness Lies Outside of Firepower

On the other hand, there are challenges indicated by this deployment. To operate Japan-U.S. equipment simultaneously in remote locations, redundancy in communications, ammunition resupply, the use of civilian ports and airports, and coordination for civilian evacuations are essential. In Okinawa, incidents involving U.S. troops have reignited opposition to the burden of bases, and military readiness alone cannot ensure the sustainability of the alliance.

The true test of Keen Sword 27 is not whether missiles can be fired. It is whether deterrence can be maintained without firing while continuing to supply the island areas when necessary. This firepower deployment is a step forward, but the alliance's vulnerabilities still lie not with the launchers but with the supply lines and political agreements.

Main Sources

• Associated Press, “Japan and the US Kick off Joint Drills Around Islands as Regional Tensions Rise,” October 19, 2026
• Defense News, “US Marine Corps anti-ship weaponry to see exercise action on remote Japan island near Taiwan,” October 5, 2026
• Ministry of Defense, Joint Staff Office announcements related to Keen Sword 27