On June 25, Defense Minister Taro Kono announced the cancellation of the planned acquisition and deployment of the Aegis Ashore system, citing the additional cost and time required for safety-related modification of the system. But the technical explanation by the government was not convincing to many observers.

Kono’s decision bravely broke rank from the LDP politicians’ reluctance to challenge Prime Minister Shinzo Abe and the bureaucratic inertia on the purchase of an expensive yet obsolete defense system Abe promised to U.S. President Donald Trump in 2017 in order to fend off the anticipated trade imbalance accusations.

The very idea of intercepting incoming ballistic missiles did not gain much traction during the Cold War, because this type of defensive system was deemed too expensive to develop. The United States and the Soviet Union chose to maintain a strategic balance between them with a negotiated nuclear parity. Deployment of missile defense arsenal was limited to one site each under the Anti-Ballistic Missile (ABM) Treaty.

The two nuclear superpowers also signed the Intermediate-range Nuclear Force (INF) Treaty in 1987, which mutually banned development, possession, and deployment of ground-based intermediate-range ballistic and cruise missiles (with a range between 500 and 5,500 km). The INF Treaty reduced uncertainties in bilateral arms control by focusing the efforts on mutual verification of the inter-continental ballistic missiles, liberating Western Europe and East Asia from the fear of being an arena of bipolar nuclear exchanges.

The abrogation of the ABM Treaty in 2002 enabled the U.S. to develop a missile defense capability to counter the intermediate- and long-range North Korean missile threat against its Asian bases that had been growing since the mid-1990s. Japan signed a memorandum of understanding on joint research of theater missile defense (TMD) with the U.S. in 1999. As the repeated testing of ballistic missiles by North Korea led Japan in late 2003 to decide on procuring missile defense platforms, especially Aegis destroyers with a high-altitude interceptive capability, the integration of U.S. and Japanese capabilities and the constitutionality of such defense cooperation became the subject of political debates in Japan.

The Abe administration in 2014 announced a reinterpretation of the Constitution to open the path to Japan’s exercise of the right to collective self-defense and passed new national security legislation the following year. The new law permits the use of force “when an armed attack against a foreign country that is in a close relationship with Japan occurs and as a result threatens Japan’s survival.”

Hypothetical scenarios of permissible collective self-defense, developed by the advisory council Abe appointed prior to the legislation, included Japanese interception of U.S.-bound ballistic missiles. However, the government largely dodged commenting on the constitutionality of Japanese interception of U.S.-bound missiles in subsequent Diet sessions, with the notable exception of Defense Minister Itsunori Onodera, who in 2017 acknowledged the “possibility” that intercepting Guam (U.S. territory and a location of key military bases)-bound missiles qualifies as permissible case.

From the beginning Japan’s participation in missile defense was inherently bound in bilateral collective defense, but the government has employed false rhetoric to disguise it as unilateral self-defense. This rhetoric assigned the principle role to Japan and the supplementary role to the U.S. for defending against Japan-bound missiles. The government pitched Aegis Ashore on territorial self-defense grounds. Government officials are tight-lipped on the much speculated notion that the proposed locations of the Aegis Ashore deployment were chosen based on the trajectories between North Korean missile bases and U.S. bases in Guam and Hawaii.

While Japan has failed to advance collective missile defense against threats from North Korea, regional missile and nuclear threats have both grown and diversified, making the planned defense strategy and procurement obsolete. North Korea’s buildup of its missile force and testing of new types of missiles with more complex trajectories in recent years have made the Aegis system less effective. China has deployed a growing number of intermediate-range missiles in East Asia, targeting U.S. and Japanese military installations throughout the region. Both Russia and China are developing hypersonic glide vehicles that can penetrate existing missile defense shields.

Moreover, developments in the European security theater have affected East Asia as well. The Russian development of “short-range” Iskandar ballistic missiles with a range at the upper-limit of this category (500 km) has placed the U.S. at a disadvantage under the INF Treaty in Europe, where the new Russian missiles pose a threat to America’s new NATO allies in Central Europe. The Trump administration’s decision to withdraw from the INF Treaty effective in August 2019 has recast the missile competition in a complex multi-party game in the two interrelated theaters, where Russia and the U.S. simultaneously compete against each other and explore possible cooperation to counter China.

Discussions about alternative missile defense arsenals must take into full account this global strategic context. The Abe government has so far refrained from the possession of a preemptive strike capability as part of its missile defense strategy, leaving this role to the U.S. Upon the U.S. withdrawal from the INF Treaty, China had already warned Japan not to allow U.S. intermediate-range missiles on its territory.

With the cancellation of the Aegis Ashore plan, the adoption of a preemptive strike doctrine has resurfaced in Japan’s missile defense debates. Japan had already announced its own plan to develop hypersonic cruise missiles and hyper velocity gliding projectile weapons that would back a shift into a more preemptive strategic doctrine. Limiting the use of new preemptive strike capabilities to solely Japan’s territorial defense will not be possible for a simple reason: The target destinations of potentially hostile missiles that are still on the ground cannot be determined.

Russia and the U.S. have started working-level negotiations in Vienna to renew the New Strategic Arms Reduction Treaty (START), which is set to expire in February 2021. Following China’s rejection of their invitation to join the talks, the two nuclear superpowers are concurrently discussing long-range nuclear weapons reduction and developing short- and intermediate-range nuclear weapons.

The likely outcomes of the U.S.-Russia talk will be between non-agreement (a full arms race) and a limited agreement to only cap long-range nuclear weapons. Given China’s unregulated missile and nuclear development and deployment, the redeployment of ground-based intermediate-range missiles with conventional warheads seems a foregone conclusion to both the U.S. and Russia, and even the nuclear arming of those missiles is possible.

Japanese political leaders must not sidestep the strategic discussions, which inevitably involve the question of collective defense with the U.S. but ought to be much broader in perspective. Debating particular tactical platforms without full appreciation of the rapidly changing strategic environment, as most Japanese politicians do, is a waste of time. Kono’s announcement has opened a Pandora’s box of politically tough questions that the country’s defense bureaucracy may have wanted to avert.

Yoichiro Sato is a professor at Ritsumeikan Asia Pacific University in Beppu, Oita Prefecture.

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