US, Japan commence joint development of Glide Phase Interceptor

The Standard Missile-3 Block IIA missile, pictured above launching from the Pacific Missile Range Facility in Hawaii, is jointly developed by the US and Japan. The MDA said the GPI joint development with Japan will be pursued in a construct similar to that used for the SM-3 missile. (US MDA)

The US and Japan have initiated the joint development of a Glide Phase Interceptor (GPI) to counter hypersonic weapons, the US Department of Defense (DoD) announced on 18 August.

According to the DoD, during the January 2023 Security Consultative Committee (2+2) meeting, the US and Japan concurred with beginning discussions on potential joint development of a future interceptor.

Based on subsequent studies, the US DoD and the Japan Ministry of Defense (MoD) decided to initiate a GPI co-operative development programme as an important part of implementation for the 2023 US-Japan bilateral memorandum of understanding (MOU) for research, development, test, and evaluation projects, the DoD said.

“The development of a counter-hypersonic capability is a pressing need for both countries to address challenges in the Indo-Pacific region, including the emergence of offensive hypersonic and other sophisticated missile capabilities for potential acts of coercion. The GPI co-development will build upon long-standing US-Japan missile defence co-operation and strengthen the alliance deterrence posture,” the DoD added.

The Japan MoD said Japan and the US will continue to co-operate by bringing together their respective strengths in key technologies such as rocket motors, heat resistance, and seekers.

“Due to repeated missile launches and progress in the development of hypersonic weapons around Japan, missile attacks on Japan have become a real threat. So GPI is an urgent need,” the MoD said.

The GPI would contribute to improving Japan's integrated air and missile defence (IAMD) capabilities, the MoD said.