The United States has long encouraged Japan, as one of its close military allies, to build up its defensive capabilities. Despite its pacifist constitution, Japan proved a critical military ally during and after the Cold War, when its prowess in anti-submarine and mine countermeasure warfare complemented and enhanced the United States' presence in the Pacific. Focused exclusively on defense, Japan's Self-Defense Forces have deliberately eschewed offensive weaponry and forces such as nuclear submarines, fixed-wing carrier aviation, dedicated amphibious forces, large-scale airborne forces, suppression of enemy air defense capabilities, ballistic missiles or land-attack cruise missiles. Instead, Japan's military has traditionally acted as the shield to the United States' sword, providing not only a base but also protection for U.S. force projection in East Asia.
Projecting Force, a Little Bit at a Time
Over time, however, regional security and political concerns have driven Japan to normalize its military, gradually eliminating the self-imposed restrictions on it. As Prime Minister Shinzo Abe pushed for a new interpretation of Article 9 of Japan's Constitution — the clause proscribing war — the Japanese military has made incipient efforts at developing offensive capabilities. The country purchased its first aerial refueling tanker in 2008, arguing that the acquisition was necessary to extend the range of its air defense patrols, reduce fuel costs, enhance response time and assist humanitarian transport missions.
Notwithstanding its stated purpose, the small fleet of tankers that Japan has amassed since was the first in a series of incremental steps toward extending its force projection capabilities. Tokyo ordered 42 stealthy F-35A multirole fighters in December 2011. Though Japan still lacks the capability to suppress enemy air defenses, the planes' stealth features would enable Tokyo to carry out strikes on targets defended by surface-to-air missile systems regardless. In 2013, with significant assistance from the U.S. Marine Corps, Japan began transitioning its Western Army Infantry Regiment into a specialized unit well versed in offensive amphibious operations, with aims to eventually expand it into a brigade.
Of the country's advances toward offensive capabilities, though, Japan's possible interest in land attack cruise missiles is the most significant. Developing a weapon capable of land attacks, even a rudimentary one, would pave the way for Japanese forces to embrace the capability, which could be adapted for use by aircraft, surface warships and submarines. Once the weapon was introduced, future missile development projects could focus on producing more dedicated, and more deadly, land attack cruise missiles, perhaps with improved range and accuracy. The missiles not only would enable Japan to independently attack a dug-in enemy protected by anti-ship and anti-air missiles, but they would also provide the flexibility and reach to pre-emptively strike a target deep within an enemy's territory.
As Japan has normalized its military, it has increasingly deviated from its doctrines on the use of military force not only in developing and deploying offensive weaponry but also in taking a more proactive approach to defense. While this new stance affords Tokyo more latitude to use its military in pursuit of national interests, it has also alarmed regional powers, which remember very well Japan's 20th-century military campaigns against them. And though Washington encourages Japan's remilitarization, eager for its ally to assume a greater role in support of its military efforts around the world, there is a possible pitfall. The United States may find itself with an ally whose growing willingness and ability to pre-emptively respond to perceived threats or encroachments could drag Washington into conflicts it did not start.
Unlike Japan's previous incremental steps, adopting cruise missiles with land attack capabilities would be a clear and decisive break with precedent for the country's Self-Defense Forces. Land attack cruise missiles are unmistakably an offensive weapon, well-suited for long-range force projection and strikes against distant enemy targets. The deployment of these weapons would signal a new direction in Japan's defense doctrine, alarming its regional competitors and potential enemies alike. For the United States, it would serve as a reminder that Japan's progressive return to arms is a double-edged sword.