by Olawale Abaire, Warrior Editorial Fellow
Over the past three years, the U.S.-Japan Alliance has reached new heights, announcing a significant milestone in global defense dynamics. During Prime Minister KISHIDA Fumio’s official visit to Washington, D.C., the two nations decided to jointly develop the Glide Phase Interceptor (GPI), a crucial addition to their defense capabilities to counter high-end, regional hypersonic threats.
In a significant move, Japan has partnered with the United States to embark on the Glide Phase Interceptor (GPI) joint development, as announced by Japan’s Ministry of Defense (MoD). The GPI is currently a hot topic of competition among three major US defense contractors.
This announcement was made public on August 18, during a meeting at Camp David where US President Biden was hosting Japan’s Prime Minister Fumio Kishida and South Korea’s President Yoon Suk-yeol. Both the Japanese MoD and the U.S. Department of Defense (DoD) were present.
Interestingly, the need for a counter-hypersonic capability is urgent for both countries to tackle challenges in the Indo-Pacific region, including the rise of offensive hypersonic and other advanced missile capabilities that could potentially be used for coercion. The GPI co-development will enhance the long-standing U.S.-Japan missile defense cooperation and fortify the Alliance’s deterrence posture.
The GPI, a missile defense program, is designed to neutralize incoming hypersonic missiles during their glide phase of flight, which is the longest phase between launch and terminal phase. The GPI will comprise new interceptors and necessary modifications to the Aegis Weapon System for their launch. The GPI initiative is not merely a technical enhancement of existing defense systems but a profound strategic shift in the Indo-Pacific region’s security landscape.
As you know that Hypersonic weapons, capable of traveling at speeds greater than Mach 5, pose a significant challenge due to their speed, maneuverability, and altitude. Hence, the development of GPI by the U.S. and Japan is a direct response to these emerging threats, emphasizing the alliance’s adaptability and forward-thinking approach.
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This GPI has the ability to operate in the glide phase of a hypersonic weapon’s trajectory, which is when the weapon is potentially most vulnerable. This phase occurs after the boost phase and before the terminal phase, providing a critical window for interception. By focusing on this phase, the GPI aims to significantly enhance the effectiveness of missile defense systems.
When compared to systems like the THAAD (Terminal High Altitude Area Defense) and the Aegis Ballistic Missile Defense, the GPI focuses more specifically on the mid-course and glide phases of hypersonic trajectories. This specificity could potentially fill a gap in current defense capabilities, primarily designed for either boost or terminal phase interceptions.
Moreover, the joint development of the GPI underscores a significant deepening of military and technological cooperation between the U.S. and Japan. This move aligns with Japan’s recent defense strategy shift, which includes increasing its defense budget to two percent of GDP by 2027 and acquiring counterstrike capabilities, signaling a more proactive stance in regional security.
In Japan, the GPI is expected to be installed on the future ASEV – Aegis System Equipped Vessels – of the Japan Maritime Self-Defense Force (JMSDF). Strategically, the GPI project is a clear message to regional powers, notably China, about the U.S.-Japan alliance’s commitment to maintaining a “free and open Indo-Pacific.” It is a demonstration of both nations’ willingness to invest in advanced technologies to deter potential adversaries and ensure stability in the region.
Furthermore, this cooperation could encourage other alliances and partnerships, such as AUKUS (Australia, the United Kingdom, and the United States), to explore similar collaborative defense projects. The announcement during the transcript also highlighted the potential for cooperation with Australia on networked air defense architectures, indicating a trend towards multilateral defense collaborations in the region.
OLAWALE ABAIRE is a Warrior researcher, writer and analyst who has written many published nonfiction books
