The Reality of Defense along the First Island Chain in 2026 as Demonstrated by Japan-U.S. NMESIS and the Improved Type 12

During the Japan-U.S. joint integrated exercise "Keen Sword 26," which concluded on October 29, the U.S. Marine Corps deployed the NMESIS anti-ship missile and the MADIS air defense system for the first time on Yonaguni Island. Instead of placing naval vessels, ground-mobile firepower was positioned on an island approximately 110 kilometers from Taiwan. This single point transformed this exercise from a traditional maritime and aerial demonstration into a distributed denial network across the islands.

What the Combination of Equipment Signifies

NMESIS is a naval and Marine Corps expeditionary ship denial system, reportedly with a range of about 185 kilometers. Because the launchers can be moved from island to island, it is difficult to provide the enemy with fixed targets. MADIS complements short-range air defense against small unmanned aerial vehicles and other threats. In contrast, the Japan Ground Self-Defense Force combined the new Type 25 anti-ship guided missile with a range of about 1,000 kilometers, the improved Type 03 medium-range surface-to-air missile, and the Type 88 anti-ship missile.

In this exercise, which involved approximately 45,000 personnel from nine countries, the presence of HIMARS on Ishigaki Island and the U.S. Army's Typhon, relocated to Okinawa, also drew attention. The absence of an aircraft carrier strike group was not a shortcoming; rather, it demonstrated a concept of dispersing long-range firepower across multiple islands to complicate the enemy's ISR (Intelligence, Surveillance, and Reconnaissance) and attack plans.

Conditions for "Effective Denial Defense"

On October 28, Japanese Defense Minister Shinjiro Koizumi and U.S. Secretary of Defense Lloyd Austin confirmed their policy to implement "effective denial defense" along the First Island Chain. This is not merely about extending missile ranges. It requires sharing target information, changing positions after launch, maintaining resupply and reloading, and ensuring that the command systems of Japan and the U.S. make decisions on the same timeline.

From the perspective of the Japan Maritime Self-Defense Force, the greatest challenge is not the lack of firepower but the sustainability of SLOC (Sea Lines of Communication). The ports, roads, and runways on Yonaguni and Ishigaki overlap with civilian infrastructure, and the movement of heavy equipment itself pressures the lives of residents. Furthermore, in the absence of an aircraft carrier, transport ships and aircraft delivering fuel, parts, and communication equipment to dispersed ground forces could become targets of attack.

Strengthening Alliances and Political Friction

The Japanese government is working to revise security-related documents by the end of the year. While the division of roles between Japan and the U.S. is becoming clearer in terms of capabilities, discussions on preventing incidents involving U.S. Marines continue in Okinawa. The paradox is that as deterrence is strengthened, friction over the legitimacy of acceptance and training around bases also increases.

What Keen Sword 26 demonstrated is not the fortification of islands, but the difficulty of making the network connecting the islands function effectively in peacetime.

In my view, the true weakness of the Japan-U.S. alliance is not the performance of missiles. It is the speed of political decision-making to simultaneously determine movement, resupply, and evacuation before an attack occurs. While the dispersion of ground firepower is militarily rational, if coordination with residents is postponed, the first obstacle to denial defense will not be the enemy's vessels but rather the operational constraints of our own forces.

References

• Ministry of Defense Japan-U.S. Defense Ministerial Meeting Summary (October 2026)
• Mainichi/Kyodo, Japan-US defense chiefs meet in Philippines (October 28, 2026)
• Defense News, US Marine Corps anti-ship weaponry to see exercise action on remote Japan island near Taiwan (October 5, 2026)
• The Straits Times, Japan and US defence chiefs agree to boost deterrence (October 28, 2026)