As part of its drive to improve defenses in the light of increased ballistic missile threats, Japan has been given the green light to acquire 56 Raytheon RIM-161C Standard Missile-3 Block IB interceptors. On April 9 the DSCA (Defense Security Cooperation Agency) announced that the U.S. State Department has approved the Foreign Military Sale, and handed the certification to Congress for final approval. Japan had earlier requested an initial batch of eight Blk IB missiles in November 2018.
Worth an estimated $1.15 billion, the SM-3 Block IB sale includes 56 interceptors, Mk 21 storage/launch canisters, and a range of technical support and logistics services. While Raytheon is the prime contractor for the all-up interceptor rounds, BAE Systems is the industry lead for the canisters.
The SM-3 is the primary short/medium-range anti-ballistic missile (ABM) system of the United States and is deployed aboard the U.S. Navy’s Aegis vessels. It has been adapted for land-based use under the Aegis Ashore program. Japan is the only export operator of the system, having equipped several vessels with the Aegis system and the RIM-161B Block IA interceptor. Patriot PAC-3 systems provided a ground-based layer to intercept missiles that “leaked” through the Aegis belt, while Japan also operates earlier RIM-66 SM-2 surface-to-air missiles.
With an increased perceived threat, particularly that from North Korea, Japan has become concerned that the current ABM assets could become overwhelmed in a large-scale missile attack, and is looking to the Block IB to add additional defensive capability. The version employs a two-color infrared seeker and an improved throttleable guidance system to increase its kill probability. The SM-3 is a hit-to-kill weapon that uses kinetic energy alone to destroy its target. The system has been deployed by the U.S. Navy at sea since 2014, and by the Missile Defense Agency in land-based form at a site in Romania (IOC 2016) as part of the EPAA (European Phased Adaptive Approach).
Japan has been involved in the development of the next-generation SM-3 Block II, with Mitsubishi joining the Raytheon effort. This version retains the Mk 72 launch booster rocket of the Blk I, but is otherwise a new missile. Its body is wider, with a 21-inch (53-cm) diameter propulsion section providing greater range and velocity performance, in turn allowing the missile to engage intermediate-range ballistic missiles. The large-diameter clamshell nosecone allows the Blk IIA to carry a larger kill vehicle. Block IIA is intended to equip a land-based Missile Defense Agency Aegis Ashore battery in Poland from 2020.
Japan requested the sale of four Blk IIA missiles and their Mk 29 canisters in January 2018, and another 13 in November that year. The Blk IIA is intended for use on the navy’s eight Aegis vessels and with two Aegis Ashore systems.