“Your association has taken a significant role in fostering public awareness of nuclear disarmament and has led to its advancement.”
– Kazi Matsui
Mayor of Hiroshima
June 2, 2022
Japan Embracing Missile Defense
Share this

Wade Boese

Several years of U.S.-Japanese cooperation on anti-missile systems bore fruit in a successful experiment March 8. The test marked an important milestone in the two countries’ collaboration as Japan expands its missile defense activities and has emerged as the leading overseas missile defense partner of the United States .

Japan began its foray into missile defenses in 1999 with research on four components for a ship-fired missile interceptor. Now, Tokyo is preparing to host an advanced U.S. missile tracking radar, develop a more powerful missile interceptor with the United States, and deploy the initial elements of a Japanese land- and sea-based missile defense system.

The March 8 test involved one of the four products of the initial U.S.-Japanese partnership. In the experiment, a U.S. Standard Missile-3 (SM-3) interceptor 88 kilometers above the Pacific Ocean employed for the first time a Japanese-designed “clamshell” nosecone. In an actual missile intercept attempt or test involving a mock warhead, the nosecone would release a kill vehicle to collide with a target hurtling through the atmosphere. But in this case, only a telemetry device to gather data on the new nosecone’s operation was released. U.S. nosecones require the SM-3 to conduct maneuvers to eject the kill vehicle; the Japanese nosecone avoids the need for maneuvers by opening up like a clamshell.

Still, the two governments have not determined whether the clamshell nosecone will be incorporated into a future SM-3 interceptor they will build based on a new 60-centimeter rocket motor also under development by Japan. This rocket motor is supposed to increase the interceptor’s range and make it capable of destroying long-range missiles. A contract for the new interceptor is expected to be signed in April, and an inaugural intercept test is set for 2014 or 2015, a U.S. Missile Defense Agency (MDA) official told Arms Control Today March 15.

The United States has tested and deployed an earlier version of the SM-3 interceptor as part of its ship-based Aegis Ballistic Missile Defense System to counter short- to intermediate-range ballistic missiles. The system has had six hits in seven intercept attempts, and nine SM-3 interceptors have been delivered to the Navy for deployment. The Government Accountability Office (GAO), which conducts studies for Congress, reported in March that U.S. plans envision deploying about 100 of the interceptors by the end of 2011.

Japan also intends initially to employ the current SM-3 interceptor aboard its four planned missile defense ships, the first of which is expected to be ready by 2007. At the same time, Japan hopes to field four land-based Patriot Advanced Capability- 3 systems, which are supposed to destroy short-and medium-range ballistic missiles near the end of their flights. Japanese procurement plans call for eventually acquiring another 12 firing units and two backup units. Japan currently deploys six early- model Patriot systems.

Japanese interest in missile defenses is animated primarily by a perceived missile threat from North Korea, although residual concerns about China also exist. In August 1998, North Korea conducted a surprise test of a ballistic missile, which flew over Japanese territory. (See ACT, August/September 1998.)

Tokyo and Washington are intent on improving their vigilance of North Korean missile activities. Toward this end, the United States will deploy a forward-based X-band radar on Japanese territory before this year ends. A Japanese government official told Arms Control Today March 15 that the two governments are currently searching for an “optimum site.”

The new radar is supposed to provide improved tracking and discrimination information on ballistic missiles in flight. Data gathered by the radar is to be shared between Japan and the United States for operating their respective anti-missile systems.

Pentagon officials testifying at a March 9 hearing of the House Armed Services Strategic Forces Subcommittee applauded Japan ’s growing missile defense role, which totals approximately $1 billion in spending annually. Peter Flory, assistant secretary of defense for international security policy, ranked Japan as “our largest international partner.”

Australia , Denmark, Germany, Israel, Italy, and the United Kingdom also are leading U.S. missile defense partners. In addition, the 26-country NATO alliance is working to knit together a system that will allow its members’ individual battlefield anti-missile systems to operate together. The group is also exploring options for protecting their national territories.

Washington is also considering the Czech Republic , Poland, and the United Kingdom as a basing site for 10 long-range U.S. missile interceptors. An MDA spokes person told Arms Control Today in February that $56 million had been requested in the latest Pentagon budget submission to advance this project (see ACT, March 2006), but that sum actually totals $120 million, according to Flory.

Since 1985, the Pentagon has spent approximately $90 billion on anti-missile projects and foresees spending nearly $58 billion more over the next six years, according to the March GAO report.