Recent reports indicate that the United States is planning to bolster its ballistic missile defense capabilities in East Asia. In addition to the existing missile defense radar deployed in northern Japan, Washington is now considering placing more radar positions in southern Japan and possibly in the Philippines. According to the Wall Street Journal, the United States would be installing new “powerful early-warning” X-band radar. Although these new installations would ostensibly be directed at the North Korean missile threat—not at China—U.S. intentions are questionable.  To avoid a confrontation, Washington and Beijing should prioritize establishing a constructive dialogue on conventional military issues in addition to the existing strategic nuclear dialogue.  

The U.S. State Department claims that the Asian missile defense systems “are designed to defend against a missile threat from North Korea. They are not directed at China.” If that claim is true, the early-warning radar in Asia should be located around North Korea and along the path a missile launched by Pyongyang would follow. That way, the radar would have a better chance to monitor the missile on its early trajectory. In general, early-warning radar should be stationed as close as possible to the launch site of the threatening missile to gain maximum warning time. Geography can complicate proximate deployments, so these radars are often located further along the probable missile trajectory. A hypothetical North Korean intercontinental ballistic missile (ICBM) targeting the continental United States would go over the North Pole, so northern Japan seems to be a good location to monitor North Korean missiles aimed at the North American continent. Indeed, the first land-based X-band radar in Asia is in northern Japan.

But an early-warning radar installation in southern Japan would add very little to Washington’s capability to monitor North Korean missiles heading toward the continental United States. The new installation’s distance from the North Korean launch sites would be similar to the range of the radar in northern Japan now, but it would not be located along the trajectory of a U.S.-bound missile. The southern site may be useful to monitor North Korean missiles targeting southern Japan and therefore could address regional concerns about the North Korean missile threat, but not direct threats to the United States.

A third radar system in this region deployed in the Philippines would offer no new early-warning benefits. Such an installation would be much further from North Korea and not in the flight path of a North Korean missile targeting sites in the region or the United States.

Furthermore, X-band radar is not the ideal early-warning technology. Early-warning radar needs to search for launched missiles across a wide range of sky; the requirement for tracking accuracy is low. X-band radar, on the other hand, is good at tracking missiles with high accuracy but not at searching a large area. Therefore, X-band radar is typically used for missile defense fire control—that is, tracking and identifying incoming warheads and assessing the success of missile intercepts. For the purpose of fire control, X-band radar is always deployed forward of the intercept engagement point at the midcourse of the missile flight. For example, Adak, Alaska, on the western end of the Aleutian Islands, is a prime location to host X-band fire-control radar for missiles originating in East Asia and heading toward the North American continent.

Within the region, the X-band radar in northern Japan can be useful for intercepting ICBMs during their ascent phase. However, the new deployment of X-band radar in southern Japan and in the Philippines would not work for fire control in intercepting hypothetical North Korean ICBMs targeting the continental United States. The installation in southern Japan may be useful for fire control if the North Korean missiles targeted Japan. But the one in the Philippines would only help if the North Korean missiles targeted Australia, which does not seem to be a real concern today. That means radar in the Philippines would be almost irrelevant to defense against the North Korean missile threat claimed by the U.S. State Department.

This raises a serious question: What is the real target of these new missile defense radar installations in East Asia?

The trajectories of hypothetical ICBMs launched from sites in East Asia (including North Korea, China, and eastern Russia) and headed toward the continental United States are similar. So regardless of where in East Asia the missiles originate, the extension of the array of X-band radar to the south is geographically a bad choice if Washington hopes to protect the U.S. homeland from missile attacks originating in the region. It could be a good choice only if the system is designed for stopping missiles from India heading to the West Coast of the United States. Given the positive nature of U.S.-India strategic relations, that scenario seems unlikely.

That leaves just one probable contingency for which these new radar deployments might be useful.  The planned array of X-band radar in East Asia geographically surrounds Taiwan and could facilitate the interception of Chinese conventional medium-range missiles in the region—the radar installations would be in particularly good locations to monitor missiles launched from southern China heading toward the central Pacific Ocean. Responding to the Wall Street Journal article and despite the U.S. government’s previous statements, General Martin Dempsey, chairman of the U.S. Joint Chiefs of Staff, publically acknowledged that the new radar in southern Japan is designed to both counter China’s military and contain threats from North Korea. This differs from the position expressed by the U.S. State Department and may be closer to the real U.S. intention. The United States has long insisted on being able to project its military power throughout Asia, while China has been building up military capabilities to defend against the projection of U.S. military power on its periphery and against its vital interests. The additional anti-missile capabilities being developed by the United States are, it seems, aimed at countering Beijing’s ability to limit U.S. power projection against China.

General Dempsey’s statement highlights the danger of conventional military confrontation between the United States and China in the Asia-Pacific region. The new U.S. moves in missile defense deployment in East Asia underscore the need for more constructive U.S.-China dialogue on conventional military issues.

Over the past two decades, China and the United States have developed some useful strategic nuclear dialogues. Although the exchanges have not always been smooth, some mutual understanding and effective exchange channels have been built. For example, the concept of strategic stability is becoming a notion accepted by most participants in the strategic nuclear dialogues between the two countries. Such mutual understanding helps the two sides build confidence in their strategic nuclear relations and could play an important role in preventing destabilizing nuclear developments. However, the United States and China have not yet built mutual understandings on basic principles in the conventional military realm.

In her response to a question about whether the new systems are directed at China, State Department spokeswoman Victoria Nuland also said, “These are defensive systems. They don’t engage unless missiles have been fired.” This statement raises the question of how a conflict that would lead China to fire missiles against forces on its periphery that in turn prompted the engagement of U.S. missile defenses would start. If missiles are fired, that portends a conflict too late to prevent. Washington and Beijing should therefore make every effort to head off conflicts before they begin by finding cooperative solutions on missile defense issues.