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The Dangers of Defense

The possible strategic pitfalls of reliance on missile defense against North Korea by Emmie Bultemeier

In early August, North Korea announced that it was in the process of developing a plan to launch four missiles into the ocean near the island of Guam, a U.S. territory. Such a move would serve as a “crucial warning” to the United States to stop what North Korea perceived as escalatory talk by President Donald Trump and his administration (Chalmers and Petty 2017). Although the plan would be for the missiles to come within just miles of Guam’s shores, potentially provoking a nuclear war, the Governor of the territory had this to say about the possibility of an attack: “At this point, based on what facts are known, there is no need to have any concern regards heightening the threat level" (Chalmers and Petty 2017).

Governor Calvo’s rationale for such a calm response was that “There is a defense umbrella contained within South Korea, there is a defense umbrella for Japan, there are naval assets between Korea, Japan and Guam, and there is a missile defense system of Guam that make up a multi-level defensive umbrella” (Chalmers and Petty 2017). His intent was to reassure the people of Guam and to prevent the situation from escalating, which are noble goals, but the issue of missile defense against an adversary like North Korea is not as simple as he makes it out to be.  

Although Calvo is correct that there are several layers of defense in the U.S. and allies’ defense capabilities in the Pacific, their effectiveness against a North Korean missile attack on Guam would be far from assured. The interceptors with the highest chance of success would be from U.S. and Japanese ships equipped with SM-3 interceptors or from THAAD interceptors based in Guam (Panda 2017).

However, to claim that these systems would definitely be able to defend against a North Korean attack is an overstatement of their reliability. In the Guam scenario, we know that the North Korean plan as stated would include four missiles fired at roughly the same time; THAAD has been effective in testing environments, but has never been tested against multiple missiles at a time (Panda 2017). It could serve as a partial defense, but almost certainly would not be able to shoot down all four at once. The ship-based interceptors suffer from a similarly incomplete testing record (Missile Defense Agency 2017).

Because of this lack of reliability, the strategic considerations that come with a North Korean attack, even if only comprised of the aforementioned warning shots, would be extraordinarily complicated. The calculations of the governments, constantly adapting to the circumstances, depend substantially on the tenuous technological factors mentioned above. What would it take for Kim Jong Un to launch the missiles? Would they accurately hit their targets? How big is the risk that they hit Guam on purpose or by accident? Would the U.S. choose to launch interceptors at the incoming missiles no matter what? What legal implications would there be for an interception? Would the U.S. retaliate with a strike of its own? What would such a counterstrike entail?

These are just some of the questions that policymakers face. Even if tensions cool – most likely temporarily – the governments involved must have ready answers to these questions.

Unfortunately, the mere existence of missile defense might be responsible for adding an extra level of complexity to these calculations. The existence of a THAAD system plus the other maritime systems that could be positioned near Guam inevitably affects Kim Jong Un’s strategic calculation. His beliefs about the likelihood that his missiles are shot down affect his analysis.

Without considering Guam’s defenses, Kim Jong Un would know with close to 100% certainty that a missile attack against Guam would result in escalation and possibly devastating retaliation. Missile defense changes that— he has the option to launch missiles dangerously close to U.S. territory or even at U.S. territory with the possibility that the U.S. would shoot them down. That makes the chances of retaliation at least a bit lower, if not significantly lower. For this reason, missile defense might actually be putting us in a more precarious situation because it makes Kim Jong Un more likely to launch missiles – even when there is a low chance of intercepting every missile launched.

In addition to making an attack less risky to some extent for North Korea, missile defense also incentivizes bigger attacks. Because the capabilities of these systems are uncertain but easy to overwhelm, the enemy must launch multiple missiles rather than just one. Offensive missiles are much easier and cheaper to proliferate than the defensive measures, so countries like North Korea can produce more and more offensive missiles relatively cheaply with the knowledge that the United States cannot keep up in its production and deployment of defenses.

This unpredictability is a problem because the stakes are huge. If a North Korean attack is successful to any extent, it would hurt American credibility and the credibility of missile defense technology more broadly. It could cause erosion of the alliances with South Korea and Japan, and probably embolden North Korea to continue and increase nuclear and missile testing. Worst case scenario, it could intentionally or unintentionally ignite a nuclear or conventional war.

And the pitfalls of the systems are only magnified when discussing defense of the U.S. mainland. The systems that the U.S. uses to defend against potential intercontinental ballistic missile attacks work only around 55% of the time in tests that do not even mimic realistic conditions (Stone 2017). All of these technologies, while useful for limited defense, are not worthy of U.S. trust against major threats like North Korea.

In light of all of these considerations and the limited options moving forward, American policymakers might find traditional deterrence to be the best route against the solidifying North Korean nuclear threat. Using the incentives of mutually assured destruction and solid, clear messaging might be a more reliable defense than expensive, unpredictable, and risky systems.


Emmie Bultemeier is a former Young Leaders in Foreign and Security Policy Fellow at GCSP and a graduate student in the Master of Science in Foreign Service programme at Georgetown University.


Works Cited

Chalmers, John, and Martin Petty. "Guam governor shrugs off North Korea's mid-August strike plan." Reuters. Edited by Lincoln Feast. August 10, 2017. https://www.reuters.com/article/us-northkorea-missiles-usa-guam/guam-governor-shrugs-off-north-koreas-mid-august-strike-plan-idUSKBN1AQ07K

Missile Defense Agency. "Aegis Missile Defense Test Conducted." Missile Defence Agency. June 21, 2017. https://www.mda.mil/news/17news0006.html

Panda, Ankit. "Can Ballistic Missile Defense Shield Guam From North Korea?" Council on Foriegn Relations. August 29, 2017. https://www.cfr.org/backgrounder/can-ballistic-missile-defense-shield-guam-north-korea

Stone, Mike. "Can U.S. defend against North Korea missiles? Not everyone agrees." Reuters. July 6, 2017. https://www.reuters.com/article/us-northkorea-missiles-usa-defenses/can-u-s-defend-against-north-korea-missiles-not-everyone-agrees-idUSKBN19Q32F.