During exercise KEEN SWORD, the largest biennial joint military exercise between the United States and Japan (scheduled from October 19 to 29), the Marines will deploy the Navy-Marine Expeditionary Ship Interdiction System (NMESIS) land-based anti-ship missile system and the Marine Air Defense Integrated System (MADIS) short-range air defense system to the Japanese island of Yonaguni, the closest to Taiwan (about 110 km away), as announced by the Okinawa Defense Bureau. The first units of both systems were delivered to the 12th Marine Littoral Regiment, based on Okinawa, last July.

The 2 systems play a central role in the Marine Corps reorganization known as Force Design 2030, which favors small, highly mobile units capable of holding strategic islands. Their presence reflects the focus of this year’s exercise on maritime access denial through land-based weapon systems. With a range of about 185 km, NMESIS could strike naval units operating in the waters near Taiwan, a capability that has drawn criticism from some Chinese military analysts.

MADIS is a mobile short-range air defense system designed to protect Marine units against drones, helicopters and low-flying aircraft. The system is mounted on a pair of Joint Light Tactical Vehicle (JLTV) 4x4s and features a remotely operated turret integrating STINGER surface-to-air missiles, a 30 mm cannon and a machine gun. It is also equipped with radar, electro-optical sensors and electronic warfare equipment capable of detecting and jamming hostile drones. Thanks to its light weight and rapid redeployment capability, MADIS can accompany small Marine units as they move between islands, providing protection against air threats to missile launchers such as NMESIS.

KEEN SWORD will involve about 45,000 Japanese personnel along with contingents from 9 countries, including Australia and France. The US Army will deploy High Mobility Artillery Rocket System (HIMARS) launchers to Ishigaki island, while the Japan Ground Self-Defense Force (JGSDF) will employ the new Type-25 surface-to-ship missile, with a range of 1,000 km. With the carrier USS GEORGE WASHINGTON redeployed to the Arabian Sea, the exercise will rely heavily on land-based forces.

Yonaguni has become a particularly sensitive point amid rising tensions around Taiwan. In 2016, Japan opened a radar station on the island, while in 2022 a Chinese ballistic missile landed about 80 km from its coast. Last June, China Coast Guard vessels entered Japan’s nearby Exclusive Economic Zone (EEZ).

The local population has voiced concern over increasing military traffic on the road network, in port facilities and in the airspace. Mayor Tsuneo Uechi stated that, while recognizing the need for training activities, the island lacks the capacity to sustain military exercises that exceed its logistical and infrastructure capabilities.

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