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Japan Invests in US SM-6 Missiles to Enhance its Defense Against Missile and Enemy Aircraft Attacks.
On January 31, 2025, The U.S. Department of State approved a potential Foreign Military Sale (FMS) to the Japanese government, including Standard Missile 6 (SM-6) Block I systems and related equipment. This transaction, valued at approximately $900 million, aims to enhance Japan’s air and missile defense capabilities in response to growing regional threats in the Asia-Pacific. The Defense Security Cooperation Agency (DSCA) has officially notified the U.S. Congress of this possible sale, which is part of a broader effort to strengthen defense cooperation between the two nations.

The Arleigh-Burke class guided-missile destroyer USS John Paul Jones (DDG 53) launches a Standard Missile 6 (SM-6) during a live-fire test of the ship's aegis weapons system (Picture source: US DoD)
Japan intends to procure up to 150 SM-6 Block I missiles, along with associated equipment, including MK 21 Mod 3 vertical launchers, spare parts, and technical and logistical support. This assistance package includes engineering services, integration, and testing, handling and test equipment, as well as training programs and technical documentation. The goal is to ensure the effective integration of the SM-6 missiles within the Japan Maritime Self-Defense Force (JMSDF), particularly on its Aegis-equipped destroyers, which are a key component of the country's air and missile defense strategy.
The SM-6, developed by Raytheon, is a multi-role missile capable of intercepting terminal-phase ballistic missiles, aircraft, and cruise missiles. Its X-band active radar seeker, derived from the AMRAAM, enables beyond-line-of-sight targeting through the Cooperative Engagement Capability (CEC) sensor network. Already in service with the U.S. Navy and allied forces, the SM-6 is expected to bolster Japan’s air defense network, particularly against emerging hypersonic missile threats from regional adversaries such as China and North Korea.
The SM-6 is powered by a dual-pulse rocket motor, incorporating an SM-3 booster and an SM-2 airframe, allowing it to reach speeds exceeding Mach 3 and a range of approximately 370 km. Its advanced guidance system integrates inertial navigation, midcourse updates via Link 16, and an active radar seeker for terminal engagement, ensuring high precision against various aerial and naval targets. Beyond its defensive role, the SM-6 has also demonstrated the capability to engage surface targets, enhancing Japan’s maritime strike potential. Looking ahead, the SM-6 Block 1B variant, expected by 2027, will feature an upgraded propulsion system to extend its range and strike capabilities.
By incorporating the SM-6 into its defense systems, Japan will significantly enhance its ability to counter airborne and missile threats at greater distances, providing an added layer of protection for its fleet and critical infrastructure. The missile’s ability to engage ballistic missiles in their terminal phase strengthens Japan’s missile shield, complementing existing systems such as the Aegis Ballistic Missile Defense (BMD) and the Patriot PAC-3. Furthermore, the SM-6’s capability to engage enemy surface vessels at extended ranges introduces a new dimension to Japan’s naval strategy, reinforcing deterrence in contested waters, particularly in the East China Sea. The integration of this system will provide Japan with greater operational flexibility in responding to evolving threats while improving coordination with U.S. and allied forces in the region.
The integration of SM-6 Block I missiles into Japan’s fleet represents a significant enhancement of its defensive capabilities, particularly in countering evolving missile and aerial threats. This acquisition aligns with broader U.S.-Japan defense cooperation, aiming to reinforce deterrence amid regional tensions. Additionally, it is expected to improve interoperability between JMSDF units and U.S. Navy forces operating in the Indo-Pacific, contributing to a more coordinated regional security framework.
The primary contractor for this sale will be RTX Corporation, with manufacturing facilities located in Camden, Arkansas. At this stage, no offset agreements have been announced, though such arrangements may be discussed in future negotiations. Furthermore, the transaction will not require additional deployment of U.S. military personnel to Japan, allowing for seamless integration without affecting allied force presence in the region.
According to the U.S. Department of State, the sale will not alter the fundamental military balance in the Indo-Pacific and will not impact the operational readiness of U.S. forces. However, it reflects Japan’s continued investment in strengthening its defense posture amid increasing regional missile capabilities. The procurement of SM-6 Block I missiles is part of Japan’s broader effort to adapt to emerging security challenges and maintain stability in the Asia-Pacific region.