Glide Phase Interceptor (GPI)

A US-Japan hit-to-kill interceptor under development to defend Aegis-equipped ships and shore installations against hypersonic glide vehicles during atmospheric glide.

Overview

The Glide Phase Interceptor is a missile-development program led by the US Missile Defense Agency and Japan’s Ministry of Defense. It is intended to intercept hypersonic glide vehicles during the glide portion of their flight, before their terminal approach. The planned launch platforms are US Navy Aegis Ballistic Missile Defense destroyers and Aegis Ashore installations using the standard Vertical Launch System, according to DefenseScoop.

GPI addresses targets that travel at Mach 5 or faster and maneuver within the atmosphere. Its intended operational contribution is an earlier engagement opportunity than the fleet’s existing terminal defense. In April 2025 testimony, MDA Director Lt. Gen. Heath Collins identified SM-6 with the Sea-Based Terminal capability as the fleet’s only defense against hypersonic maneuvering targets, as documented by Defense News.

Northrop Grumman is the selected US prime contractor. Japan contributes propulsion and control components through Mitsubishi Heavy Industries. The bilateral arrangement extends the missile-defense cooperation established through SM-3 Block IIA, according to Naval News. GPI remains in development; the public record establishes neither operational deployment nor a completed interceptor flight test.

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