As hypersonic weapons reshape the Indo-Pacific security environment, regional Allies and Partners are accelerating cooperation on layered defenses to detect, track and intercept such threats.
Traveling at five times the speed of sound, about 6,100 kilometers per hour, hypersonic weapons compress decision times and complicate traditional missile defenses. Unlike ballistic missiles that follow predictable paths, hypersonic glide vehicles fly at lower altitudes and maneuver throughout flight, making them harder to detect and intercept.
“Hypersonic weapons alter the deterrence equation by virtue of their speed, by providing the means to rapidly degrade an opponent’s regional forces … before the opponent can effectively respond,” Dean Wilkening, a nonresident senior fellow with the United States-based Atlantic Council’s Forward Defense program, told FORUM. “Their maneuverability provides a capability to penetrate regional defenses, thus rendering legacy defensive networks relatively ineffective.”
That has spurred nations to emphasize integrated defense architectures that provide multiple opportunities to defeat incoming missiles during flight.
“This is important for hypersonic threats because intercepts during their glide phase may be easier than during their terminal phase,” Wilkening said.
A key example of allied cooperation is the Japan-U.S. Glide Phase Interceptor (GPI), designed to engage hypersonic glide vehicles before they begin their final descent toward a target. The program is being developed by Japan’s Defense Ministry and the U.S. Missile Defense Agency.
Designed to integrate with the Aegis Combat System deployed on Japanese and U.S. destroyers, the interceptor will target hypersonic vehicles during their vulnerable glide phase.
The strategic importance of hypersonic technologies also is reflected in allied efforts to develop capabilities that reinforce deterrence, Wilkening said.
For example, Tokyo initiated its Hyper Velocity Gliding Projectile program to defend its southwestern island chain and maintain deterrence in the East China Sea. Variants are expected to provide extended-range capability against maritime targets as part of Japan’s strengthening of its counterstrike capacity.
According to Japan’s Defense Ministry, hypersonic weapons are part of an evolving missile threat environment in East Asia that demands closer coordination with allies.
Countering such threats requires advances not only in interceptors but also in early warning and tracking systems, analysts say. Shared sensor networks, particularly space-based infrared systems capable of tracking missiles throughout their trajectories, “are key to developing the warning and tracking ability to guide these interceptors,” Wilkening said.
Multilateral frameworks, such as the AUKUS partnership among Australia, the United Kingdom and the U.S., also are emerging to address the challenge, while regional exercises and joint missile defense initiatives enhance interoperability.
Jonathan Rosenstein, assistant director of the Forward Defense program, said hypersonic systems are particularly relevant to the operational challenges of the Indo-Pacific theater, where long distances and contested environments shape military planning.
“In an Indo-Pacific contingency, allied forces will need to operate in a highly contested environment and penetrate … anti-access/area-denial architecture,” Rosenstein told FORUM. Hypersonic weapons can hold targets at risk across vast distances without pre-positioning assets inside the threat area, “offering a meaningful operational advantage in a theater defined by geography.”