“Strengthening Deterrence Against China Through Joint Weapons Production”: U.S.-Japan Defense Industry Cooperation Accelerates, Heightening Military Tensions in Northeast Asia

U.S. and Japan strengthen defense industry cooperation, agree to assemble AMRAAM missiles in Japan
Long-range strike and missile defense capabilities expanded in preparation for a Taiwan contingency
China faces mounting military pressure, expands maritime and aerial military activities around Japan

The United States and Japan have agreed to establish a final assembly and testing facility in Japan for the AIM-120 AMRAAM, a leading air-to-air missile used by their fighter jets. Amid rising tensions over the Taiwan Strait and the East China Sea, the two countries are drawing on Japan’s industrial base to strengthen weapons production and supply capabilities in the Indo-Pacific. They are also expanding cooperation beyond AMRAAM to include SM-3 and PAC-3 MSE missiles and drones, bolstering their ability to sustain prolonged operations and their defense capabilities in a contingency.

AMRAAM Final Assembly Hub to Be Established in Japan

On the 29th, local time, the Nihon Keizai Shimbun (Nikkei) reported that Japan and the United States had agreed to establish a final assembly and inspection facility in Japan for the AMRAAM medium-range air-to-air missile. Japanese Defense Minister Shinjiro Koizumi finalized the plan during a roughly 30-minute meeting with U.S. Defense Secretary Pete Hegseth on the sidelines of the ASEAN Defence Ministers’ Meeting-Plus (ADMM-Plus) in Cebu, the Philippines, on the 28th. At a press conference immediately after the meeting, Koizumi said, “We have reached a final agreement to establish a final assembly and inspection facility in Japan for AMRAAM missiles, which are essential for F-35 fighter jets,” adding, “This will contribute to securing stable supplies of defense equipment for both countries and strengthening Japan’s defense industrial base.”

AMRAAM is an advanced medium-range air-to-air missile produced by Raytheon, a subsidiary of U.S. defense contractor RTX, and is used by fighter jets to strike enemy aircraft beyond visual range. During the initial phase of flight, it uses targeting information supplied by fighter jets and other platforms; in the terminal phase, it tracks its target with its own active radar seeker. It is one of the main weapons carried by the Japan Air Self-Defense Force’s F-35 stealth fighters and is also used in the ground-based air defense system NASAMS.

China Strongly Objects, Calling It a “Challenge to the Postwar International Order”

The Chinese government has strongly objected to the agreement between the United States and Japan. Responding to a question at a regular briefing on the 29th, Chinese Foreign Ministry spokesperson Guo Jiakun warned, “In developing bilateral relations and pursuing security cooperation, the United States and Japan must not undermine regional peace and stability, target other countries, or infringe on the interests of third countries.” He continued, “Since taking office, the current Japanese government has continually pushed beyond the constraints of international and domestic law under the pretext of responding to threats,” criticizing this as “an act that challenges the postwar international order and threatens regional peace and stability.” He urged the international community to “remain highly vigilant and resolutely stop such moves.”

At a briefing on the 23rd of last month, Guo also said that the Japanese government was continuing its military buildup while denying its history of aggression and glorifying war crimes. He argued that Japan was undermining the postwar international order by seeking to abolish its USD 0.00 non-nuclear principles and amend its pacifist constitution. On the 16th, Foreign Ministry spokesperson Mao Ning also raised the possibility that the Japanese government could ease restrictions on bringing nuclear weapons into the country, emphasizing, “As a country defeated in World War II and a party to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), Japan has an obligation under international law to adhere to an exclusively defense-oriented policy and not possess nuclear weapons.”

Japan Moves to Strengthen Long-Range Strike Capabilities

China’s heightened vigilance toward Japan is seen as rooted in diplomatic and security disputes between the two countries that intensified in November last year. The immediate trigger was a statement by Japanese Prime Minister Sanae Takaichi at a House of Representatives Budget Committee meeting on November 7 last year. Takaichi said that if China used warships to exercise force against Taiwan, it could constitute a “survival-threatening situation” under Japan’s security legislation, allowing the country to exercise its right to collective self-defense. China strongly objected, accusing Japan of seeking to intervene militarily in the Taiwan issue. Since then, the two countries’ confrontation has extended beyond diplomatic exchanges to friction in trade, security, and other areas.

Against this backdrop, Japan has stepped up efforts to improve its long-range strike capabilities. According to Kyodo News, Japan’s Defense Ministry deployed domestically produced long-range missiles for operational use for the first time in March at Camp Kengun in Kumamoto Prefecture, Kyushu, and Camp Fuji in Shizuoka Prefecture. This marked the first time Japan had translated the “counterstrike capabilities” specified in its revised 2022 National Security Strategy into an operational force. The two countries are also strengthening their joint operational capabilities as the United States makes active use of military sites on Japan’s southwestern islands. During the large-scale joint exercise Keen Sword 27, held from the 19th to the 29th of this month, the United States and Japan had planned to deploy the U.S. military’s NMESIS ground-based anti-ship missile system and MADIS short-range air defense system to Japan’s Yonaguni Island, near Taiwan, for the first time. However, local media, including Ryukyu Broadcasting, reported that the deployments were canceled after a typhoon forced the exercise to be scaled back.

Table 1. Japan’s Efforts to Improve Long-Range Strike and Defense Capabilities

U.S.-Japan Defense Industry Cooperation Deepens

The scope of defense industry cooperation between the United States and Japan is also steadily expanding. Kyodo News reported in April that the two governments were pursuing plans to establish a new public-private cooperation framework by the end of the year to jointly develop and produce advanced defense equipment using dual-use technologies. The first project reportedly under consideration was a plan to produce drones developed by U.S. startups in Japan. In May, Defense Minister Koizumi and U.S. Ambassador to Japan George Glass jointly visited a production facility operated by Japanese drone manufacturer Prodrone, signaling their interest in industrial cooperation in the sector. However, the specific companies participating in the project and its production schedule have yet to be disclosed.

In the missile sector, discussions on expanding production capacity have become more concrete. At the U.S.-Japan Defense Industrial Cooperation, Acquisition and Sustainment forum (DICAS 2.0) in April, the two countries reaffirmed plans to increase production of the jointly developed SM-3 Block IIA sea-based ballistic missile interceptor approximately fourfold. In August, the U.S. Defense Department signed framework agreements with Boeing and RTX to expand supplies of key components for the SM-3 missile family. The two countries are also discussing ways to strengthen their joint production capacity for PAC-3 MSE interceptor missiles used in the Patriot air defense system. Japan’s Defense Ministry said in May that Koizumi and Ambassador Glass had jointly toured a Mitsubishi Heavy Industries missile manufacturing facility and that it would accelerate its review of measures to improve production efficiency and supply chain stability.

China Moves to Counter Developments Near Japan

This expansion of U.S.-Japan defense industry cooperation is expected to place considerable military pressure on China. If the United States uses Japan’s industrial base to diversify its weapons production and supply hubs in the Indo-Pacific, China would face a greater burden should it take military action in the Taiwan Strait or the East China Sea. In particular, expanded production capacity for interceptors such as the SM-3 and PAC-3 MSE could improve the endurance of air and missile defense networks countering China’s ballistic missile forces. Joint drone production and stronger procurement systems for aircraft armaments are also seen as supporting the two countries’ ability to conduct joint operations in a contingency.

Against this backdrop, China is stepping up its vigilance by expanding military activities in waters around Japan. According to Japan’s Defense Ministry, at around 10 a.m. on the 27th, a total of 4 Chinese vessels—2 naval guided-missile destroyers, 1 frigate, and 1 coast guard ship—passed through the Osumi Strait, south of Kagoshima Prefecture in Kyushu, into the Pacific Ocean. This was the first officially confirmed instance of Chinese naval vessels and a coast guard ship passing together through waters around Japan. On the 28th, 1 Chinese military reconnaissance drone and 1 intelligence-gathering aircraft passed between Okinawa’s main island and Miyakojima into the Pacific before returning. On the same day, 1 Chinese military patrol aircraft was also confirmed to have flown near Nagasaki Prefecture and over waters northwest of Okinawa.