Japan's New Missile and the Future of U.S.-Japan Defense Relations

In August, the government of Japan outlined plans to domestically produce a new surface-to-ship missile (SSM). This missile will have a range of 300 kilometers with a planned deployment date of 2023. It is likely that the missile will be deployed to the Miyako and Yaeyama island chains in the southern part of the Okinawa prefecture. From there, the missiles will be able to strike targets approaching the remote Senkaku island chain. These small islands have been a contentious issue in Sino-Japanese relations in recent years, particularly due to recent Chinese encroachments in the area. This deployment appears to be part of a small-scale version of the anti-access/area denial (A2/AD) operational concept being developed by the Chinese military, which emphasizes the use of long-range striking power aided by sensors, largely in the form of ballistic and cruise missiles, to hit naval surface forces and fixed targets on land and has caused a great deal of consternation in American military circles. This procurement should provide durable capabilities to defend Japanese territorial claims in the event of a conflict, assuming sensors can maintain coverage of the area around the Senkaku islands.

Since World War II, Japan has not purchased much in the way of “offensive” weaponry that could be used to project force. The procurement of a new SSM is not a major departure from this trend, though. Japan already deploys land-based missiles in the region with ranges of 200 km. It is possible that these new missiles could be mounted on aircraft or ships to increase force-projection capabilities, but the platforms carrying the missiles would be vulnerable to attack while attempting to get in range for a missile launch, assuming an adversary with comparable missiles.

By itself, the SSM procurement does not radically alter the nature of the U.S.-Japan military alliance. Japan could use the SSM to augment its ability to defend or deter aggressive behavior around the Senkaku islands in a minor conflict, meaning the United States would not need to be as involved in the issue. Japan could also use the missiles as part of a broader, high-intensity counter A2/AD campaign against China. Such a conflict appears unlikely, but the U.S. military has taken interest in the threat A2/AD could pose in the western Pacific. 

What impact the missiles would have in such a war is dependent on what operational concept is decided upon to counter A2/AD. The U.S. military has historically favored offensive operations. When combined with the potential to procure more advanced weaponry, it is not surprising that the American military is leaning toward the aggressive Joint Concept for Access and Maneuver in the Global Commons (JAM-GC) (formerly referred to as the Air/Sea Battle concept) to counter Chinese A2/AD capabilities. JAM-GC Battle plans to destroy the Chinese weapon systems that make it possible to conduct an A2/AD campaign. The Japanese missile’s limited range means it cannot strike missile launchers or other targets on the Chinese mainland that enable A2/AD.

Other options with less ambitious objectives have been proposed to counter A2/AD.  They primarily fall under the categories of denying China the area it seeks to deny others or using a blockade to coerce China into halting aggressive actions. The greater coverage of the SSMs compared to the ones currently deployed would strengthen the capabilities of the U.S. military and the Japanese Self-Defense Forces to deny China access to its near seas on the margin. Alternatively, SSMs could be stationed on the Japanese islands south of Kyushu to assist in a coercive blockade of China. In sum, the deployment would do little to defeat China’s A2/AD threat directly, but could moderately enhance indirect counter moves.

Although the SSM being planned does not radically alter the military dynamics of East Asia, it is possible that Japan could acquire more aggressive weaponry in the future. For instance, the Japanese government could build on the technology to create a new missile with greater range. Such a weapon would expand Japan’s own A2/AD capabilities while allowing the country to take a greater role in providing for its own security.   

A policy like this could occur if the United States presses Japan to play a greater role in an aggressive A2/AD campaign. Another way Japan could be motivated to acquire more force projection abilities would be if Tokyo perceived its interests were threatened even with American security guarantees. Plans to procure more offensive weapons could be politically constrained by the non-interventionist views many Japanese citizens hold.

If Japan increased its offensive capability due to such pressures, it could be a double-edged sword for the United States. On the one hand, Americans have often called for Japan to take a more prominent role in defending itself, including President-elect Donald Trump. Doing so could be a balance against China’s growing military capabilities. It would also ease the defense burden of the United States in East Asia. On the other hand, Japan would have greater capability to assert its own interests independent of American wishes. In a heated confrontation over the Senkaku islands dispute, for example, Tokyo could be more willing than Washington to take quick action. The United States has reassured Japan that it would defend the islands; however, Tokyo may wish for more prompt and aggressive responses than Washington would desire. Determining the optimal degree of expanded military capabilities of its longtime ally will thus be a challenge for the United States. 

Ben Wermeling is a recent graduate of George Washington University's graduate program in security studies and a defense policy researcher.