U.S. and Japan Make Mass Missile Deployments Near Taiwan Under Largest Ever ‘Keen Sword’ Exercises

The United States and Japan have launched their largest-ever Keen Sword joint military exercise, bringing together approximately 57,000 American and Japanese personnel for manoeuvres running from October 19 to 29. The exercise will see Japan deploy its newly introduced Type 25 surface-to-ship missile system outside its permanent base for the first time, while the U.S. Marine Corps will deploy its Navy-Marine Expeditionary Ship Interdiction System (NMESIS) to Yonaguni Island, approximately 110 kilometres from Taiwan Island. The manoeuvres are intended to test the rapid deployment of forces and anti-ship capabilities across Japan’s southwestern island chain, in an area that is expected to be a focal point for a potential Taiwan Strait war. 

The Japanese Ground Self-Defense Force began moving Type 25 missile launchers and associated equipment from Camp Kengun in Kumamoto Prefecture on October 18 to the Oyanohara training area, spanning Nagasaki and Saga prefectures. The deployment marks the first time the system has been taken outside its permanent base since entering service in March 2026. The exercise will involve simulated engagements against enemy vessels, with Japanese and American forces sharing targeting information and rehearsing missile launch procedures, but no live firing of the Type 25 is planned. The Type 25 surface-to-ship missile provides a substantially greater range than its predecessor the Type 12, reportedly reaching approximately 1,000 kilometres, allowing forces operating from Kyushu to threaten maritime targets across much of the East China Sea including across much of the Chinese mainland’s coastline. 

Taking centre stage in the exercises, the U.S. Marine Corps plans to bring its NMESIS system combines a remotely operated launcher with Naval Strike Missiles, providing a mobile ground-based anti-ship capability designed to engage surface vessels from dispersed positions. The deployment will test the movement and operation of these systems in an island environment close to key maritime approaches. It will be complemented by Japanese deployments of Type 88 anti-ship missiles and Type 03 medium-range surface-to-air missile systems to Yonaguni, and additional Type 88 systems to nearby Ishigaki Island. These systems are expected to contribute different elements to a layered defence. The exercises’ focus on these systems reflect a reorientation of both U.S. and Japanese forces to focus on asymmetric assets in a potential conflict in East Asia, in order to offset Chinese forces’ increasingly vast conventional advances.