Deterrence under nuclear asymmetry: THAAD and the prospects for missile defense on the Korean peninsula

ABSTRACT

The 2016 decision to deploy Terminal High Altitude Area Defense (THAAD) to South Korea has generated multitude of intensely politicized issues and has proved highly controversial. This has made it challenging to alleviate, let alone clarify, points of analytical and policy tensions. We instead disaggregate and revisit two fundamental questions. One is whether THAAD could really defend South Korea from North Korean missiles. We challenge the conventional “qualified optimism” by giving analytical primacy to three countermeasures available to defeat THAAD–use of decoys, tumbling and spiral motion, and outnumbering. These countermeasures are relatively inexpensive to create but exceedingly difficult to offset. Second, we assess the optimal way to ensure South Korean national security against North Korean missiles. By examining the balance of capability and issues of credibility/commitment, we show that the U.S. extended deterrence by punishment remains plentiful and sufficiently credible even without enhancing the current defense capability.

KEYWORDS:

• Security dilemma
• ballistic missile defense (BMD)
• terminal high altitude area defense (THAAD)
• extended deterrence
• North Korea

Acknowledgements

The authors thank Paul Avey, Charles Glaser, Mike Mochizuki, Seung Joon Paik, Kimberly Peh, and two anonymous reviewers for their helpful comments. Previous drafts of this article were presented at the ISA Hong Kong and ISA ISSS-ISAC Washington, DC in 2017. For valuable research assistance, the authors thank Kian Yang Tan.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Inwook Kim is Assistant Professor of Political Science in the School of Social Sciences, Singapore Management University.

Soul Park is an Assistant Professor; a Lecturer in International Relations in the Department of Political Science, National University of Singapore.

ORCID

Inwook Kim http://orcid.org/0000-0002-0012-7701

Soul Park http://orcid.org/0000-0001-6692-9080

Notes

1. THAAD is a latest ballistic missile defense (BMD) system developed in the United States, designed to intercept short, medium, and intermediate range ballistic missiles at their terminal flight stage. While THAAD debate is shaped by North Korea’s growing nuclear threats, the THAAD interception capability technically covers both missiles armed with conventional and nuclear warheads. For technical specifications, components, defense capability, and history of THAAD, see Center for Strategic and International Studies (2017). The U.S. Forces in Korea (USFK) deployed one battery of THAAD in March 2017 which became operational in May. It is stationed in Seongju, the southeastern region of the Korean Peninsula. See (Choe, 2017).

2. The debate intensified after North Korea fired a Nodong missile to high altitude on March 2014. This unprecedented launch pattern raised a suspicion that Pyongyang is seeking to exploit a technical gap in the existing PAC-3 system, which can intercept incoming missiles at lower altitude only (Chosun Ilbo, 2014).

3. The tension reached its peak when President Trump remarked, “why are we paying a billion dollars? So I informed South Korea if it could be appropriate if they paid … We’re going to protect them. But they should pay that … ” (Reuters, 2017).

4. SSPk is defined as “the probability an individual interceptor will collide with and destroy a missile or warhead” (Elleman & Zagurek, 2016, pp. 5–6).

5. Indeed, many critics contend that Pyongyang’s ballistic missile program is eyeing at Alaska and the U.S. western coast, which requires missile flight out of the atmosphere and reentry technology.

6. Suh (2017) raises an action-reaction possibility but falls short in detailing countermeasures.

7. We exclude one other major countermeasure, preemptive strike on the BMD system. See Sessler et al. (2000, p. 48).

8. The X-Band radar has two modes – Terminal Mode (TM) and Forward Base Mode (FBM). TM operates a shorter range than FBM. It is reported that the X-Band in South Korea would operate on TM as the radar is expected to not only detect, but acquire, track, and discriminate ballistic missiles in the terminal phase of flight. (Raytheon, n.d.).

9. This is a slight variation from Wilkening (2000, pp. 191–194) which divides countermeasures into “circumvention,” “defense suppression,” “saturation,” and “qualitative improvement in the offense.”

10. Other countermeasures include cutting a rocket into multiple pieces creating potential alternative targets for interceptors. They are, however, more useful against the GMD. X-Band with TM (as set up in South Korea) is reportedly able to discriminate a real warhead.

11. It is estimated that North Korea has no less than 200 missile launchers (Office of the Secretary of Defense, 2017, p. 17).

12. The Chevaline Project, the British initiative in the 1970s to develop missile technology capable of penetrating the Moscow’s ABM, allegedly cost £1,000 million by 1980 (Baylis & Stoddart, 2003). The cost and technology have becoming less prohibitive over the years, however (Sessler et al., 2000, p. 39).

13. The U.S. Air Force will be committing 60% of combat F-22s to the region (Cordesman & Linn, 2015, pp. 29–30).