China should not fear US missile deployment in South Korea

North Korea’s recent nuclear and missile tests have catalysed negotiations between Washington and Seoul on deploying the Terminal High Altitude Area Defence (Thaad) system to South Korea. Washington and Seoul hope the missile system can provide an additional layer of protection for South Korea and the US troops stationed there by intercepting North Korean missiles at high altitudes, thus serving as a complement to South Korea’s existing low-altitude missile defence systems.

Beijing has long opposed such deployment out of concern that it is part of a US strategy to build a regional missile defence network that could intercept Chinese missiles headed for the US and hence blunt China’s nuclear retaliation capability and undermine deterrence.

In recent months, Chinese official reaction to the US and South Korean decision to move forward on Thaad negotiations has been particularly harsh. There is even discussion in China that if Washington and Seoul go ahead and deploy the defence system, China may need to further build up its nuclear capability, risking a counter-reaction from the United States. Avoiding this kind of negative action-reaction cycle is critical for regional stability. It is also a necessary precondition for these countries to work together to address the more pressing security challenge faced by everyone: North Korea’s growing nuclear threat.

US offers to brief China over deployment of THAAD missile system in South Korea

Many Chinese strategists seem to harbour major misunderstandings about what Thaad could do if deployed in South Korea. They believe it is best suited to intercept medium- and intermediate-range ballistic missiles, which have ranges of between 500km and 5,500km. Because the entire Korean peninsula is only about 900km from north to south, these strategists argue that the system won’t be able to defend against the primary missile threat that South Korea faces – short-range missiles from North Korea. As a result, they suspect that Thaad deployment is really about undermining China’s strategic security interests. A particular concern is that the radar associated with the system might be used to monitor Chinese intercontinental ballistic missiles launched from the northeast and from submarines in the Yellow Sea.

In fact, Thaad is designed to defeat both short- and medium-range missiles and most tests have so far involved intercepting short-range missiles. Besides, North Korea could use medium- or intermediate-range missiles to strike South Korean targets by firing them at a higher angle, like a lob shot in tennis. Missile attacks of this kind cannot be addressed by South Korea’s current defences. To make matters worse, nuclear warheads on an incoming missile can be set to detonate at high altitude, but South Korea’s existing missile defence systems are capable only of conducting low-altitude intercepts.