Tempers in North Korea and the United States are rising amid speculation that Pyongyang has successfully fitted a miniaturized nuclear warhead onto one of its missiles. And now the Trump administration has accelerated its deployment of a missile defense system in South Korea, known as Terminal High Altitude Area Defense (THAAD), which is meant to protect both U.S. forces in Asia and American allies in South Korea and Japan from a North Korean attack.

Yet in contrast to U.S.-led missile defense projects in Eastern Europe and the Middle East, THAAD is not particularly welcome in South Korea. The country’s president, Moon Jae-in, has sent mixed signals about the deployment and many of his people are actively opposed to it. In fact, South Koreans have protested en masse against THAAD, with many concerned that it will further destabilize the region. China is angry, claiming that the missile defense radar system peers into its territory and poses a military threat. It has even initiated economic sanctions against South Korea in response. Russia has likewise voiced strong objections, just as it has done over NATO’s missile defense system in Europe. Rather than making the region more secure, it appears that THAAD could lead to a further escalation in tensions.

Paradoxically, the United States has traditionally viewed its missile defense systems as a means of encouraging stability by deterring revisionist states from attacking U.S. allies. The U.S. missile defense policy converged neatly with the Obama administration’s distaste of using military force. The idea was that if vulnerable U.S. allies had effective defenses, the United States would not need to carry out pre-emptive strikes against the source of a missile threat. And so the administration closely co-operated with Israel on the development and funding of the Arrow-3 system, which was intended to address a potential nuclear threat from Iran.

In contrast to U.S.-led missile defense projects in Eastern Europe and the Middle East, THAAD is not particularly welcome in South Korea.

But such programs might have been the lowest-hanging fruit. Although the Israelis have taken pride in the missile defense cooperation with the United States, as have the Poles, East Asia is more complicated. Some see missile defense deployments in South Korea as an unnecessary provocation of China. Moon, for example, seeks better relations with both North Korea and China, and as the scholar Katharine Moon pointed out in Foreign Affairs, his election campaign included promises to open a dialogue with Pyongyang and repair relations with Beijing.

South Korean concerns about THAAD will only be exacerbated further by the remarks of some U.S. officials and lawmakers that a preventive strike on North Korea would be preferable to waiting until Pyongyang has the means to deliver a nuclear attack on the United States, even if there is a humanitarian catastrophe in East Asia. For example, Republican Senator Lindsey Graham of South Carolina said earlier in August, “If thousands die, they’re going to die over there. They’re not going to die here. And [Trump has] told me that to my face.” 

THAAD protestors in Seongju, June 2017.
Kim Hong-ji / Reuters

The U.S. missile defense program is more rightly viewed as a hedge against deterrence failure. China’s complaints over THAAD are wrong-headed since North Korea poses a grave and immediate threat to South Korea and Japan. By deploying missile defence systems in East Asia, the United States is reinforcing its security commitments to its allies in the region. In view of the fact that some 11 million people live in Seoul (one in five South Koreans), which is just 35 miles from the border with North Korea, they are vulnerable to an attack from Pyongyang. Thus a U.S. security commitment must utilize all the resources at its disposal to protect its ally, exemplified through missile defense. If there are no systems in place to intercept a North Korean missile barrage, many hundreds of thousands could be killed. In such a scenario, the United States would struggle to minimize the scope of the conflict, amid the suffering in South Korea.

Missile defenses, moreover, can also play an important role in strengthening public morale in a conflict situation. One need only look at what the Iron Dome system did to boost Israeli morale during the wars with Hamas in 2012 and 2014.

Unless there is clear intelligence pointing to an imminent North Korean strike against U.S. allies or targets in East Asia, it seems that an American preventive attack is unlikely. For a start, tens of thousands of Americans could be targeted in North Korean counter-strikes, as well as South Koreans and Japanese. Furthermore, if the United States attacked North Korea in the face of objections by its allies in East Asia, it would have catastrophic implications for the U.S. system of alliances. The United States has forged alliances throughout the globe based on the notion that Washington will protect its friends in the face of adversity. An ill-conceived action that endangers allies in East Asia will diminish the trust, and will have a damaging impact on other U.S. alliances, including NATO.

The United States is in a tough spot, of course. No U.S. administration wants a humanitarian disaster in South Korea, but the options for deterring North Korea are limited. But, THAAD can still provide some insurance. It cannot hermetically seal South Korea off from a North Korean missile barrage—and if even one conventional missile gets through, let alone a nuclear missile, the destruction would be mind boggling. Yet, the idea behind missile defense is to dissuade a revisionist state, such as North Korea, from pursuing aggression to begin with. Pyongyang must consider the strong probability that Seoul’s retaliatory capabilities would survive intact as a result of the defensive system.

This is known in the field as “deterrence by denial”: THAAD cannot provide cast-iron guarantees but it sends the message to Pyongyang that the success of a missile barrage against South Korean cities is not guaranteed either. This was how Israel succeeded in diminishing the threat and impact of Hamas’ rockets through Iron Dome in 2014. And this is what the United States is aiming for with its controversial deployment of THAAD: to prevent unrestrained conflict between the two Koreas. The deployment of THAAD, in short, is a case of mitigating the worst effects of a war, the consequences of which will be unimaginable. 

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