Inherent Right of Self-Defense Through the Lens of the 2010 Cheonan Attack

• Author: Sangjae Lee
• Position: Judge Advocate, Army of the Republic of Korea. Presently assigned as Chief of Military Trial Department, Army Headquarters. LL.M., 2011,. The Judge Advocate General's School, U.S. Army, Charlottesville, Virginia,. Masters of Laws (LL.M), 2006, Korea University at Seoul; Bachelor of Laws (LL.B), 1997, Kyunghee University at Seoul. Previous...
• Pages: 212-233

212 MILITARY LAW REVIEW [Vol. 216

INHERENT RIGHT OF SELF-DEFENSE

THROUGH THE LENS OF THE 2010 CHEONAN ATTACK

LIEUTENANT COLONEL SANGJAE LEE

I. Introduction

A Republic of Korea (ROK) Navy ship (Cheonan), with 104 crew

members on board, sank near the western maritime border with North

Korea after a mysterious explosion on March 26, 2010.1 Forty-six

Korean Navy sailors were killed in this unprecedented tragedy, the cause

of which could not be immediately identified. After a long and thorough

investigation on the cause of the explosion, a ROK-led multinational

investigation team—composed of international experts from ROK,

United States, United Kingdom, Canada, Australia, and Sweden—

concluded that the warship had been sunk by a North Korean torpedo

fired by a submarine.2 Immediately after the investigation report was

completed, the President of the ROK vowed to exercise the right of self-

defense if North Korea attempted military provocation again.3

Academic controversy exists over whether the ROK had a right of

self-defense once it determined that North Korea had perpetrated the

attack. Understandably, due to the gravity and seriousness of the

* Judge Advocate, Army of the Republic of Korea. Presently assigned as Chief of

Military Trial Department, Army Headquarters. LL.M., 2011,. The Judge Advocate

General’s School, U.S. Army, Charlottesville, Virginia,. Masters of Laws (LL.M), 2006,

Korea University at Seoul; Bachelor of Laws (LL.B), 1997, Kyunghee University at

Seoul. Previous assignments include SJA, 50th Division of Korean Army, Daegu, 2009;

Chief of Legal Affairs Department, SROKA, Daegu, 2007–2009; SJA, 32nd Division of

Korean Army, Daejeon, 2005–2007; Military Judge, Zaytun Division, Arbil, Iraq, 2004–

2005; Military Judge, 9th Corps of Korean Army, Jeonju, 2003–2004. Member of the

Korean Bar Association. This article was submitted in partial completion of the Master of

Laws requirements of the 59th Judge Advocate Officer Graduate Course. The author

thanks Major Jeremy Marsh for his inspirational comments on the topic selection. The

author thanks Major Robert Barnsby for his guidance as paper advisor. The author

dedicates this paper to the forty-six fellow sailors who sacrificed themselves while

defending their country. We all know that freedom is not free.

1 MINISTRY OF NAT’L DEF., REPUBLIC OF KOREA, JOINT INVESTIGATION REPORT ON THE

ATTACK AGAINST ROK SHIP CHEONAN (2010).

2 On May 20, 2010, the team presented a summary of their investigation. On September

13, 2010, the ROK government released the final report, reaffirming that it was a North

Korean attack. See id.

3 So-hyun Kim, Lee Says South Will Invoke Right of Self-Defense, KOREA HERALD, May

24, 2010, http://www.koreaherald.com/national/Detail.jsp?newsMLId=20100524000740.

2012] SELF-DEFENSE & 2010 CHEONAN ATTACK 213

incident, the ROK government wanted to conduct a thorough and

objective investigation before assigning a cause. This took considerable

time (fifty-five days), thereby raising the issue of whether immediacy is a

requirement in exercising the right of self-defense.4 In other words, if

immediacy of a military response is required, the right of self-defense

would be difficult to exercise where the aggressor in an attack is not

identified until after a significant period of time has elapsed.

Traditionally, necessity and proportionality are considered to be the

most important criteria comprising the right of self-defense under

international law.5 In addition to these two criteria, some commentators

have argued that immediacy is a separate requirement when exercising

the right of self-defense.6 According to this argument, a response may

not be undertaken in self-defense after a period of time has elapsed since

the armed attack.7 Rather than emphasizing immediacy as a separate

requirement to the exercise of the right of self-defense, timeliness of a

response should only be one of many factors when considering the

necessity of exercising the right of self-defense.

This article explores how the concept of the right of self-defense has

evolved in the field of international law, and also provides the legal

analysis of the criteria of the right of self-defense, traditionally referred

to as necessity and proportionality in Part II. Part III examines the role of

time in the exercise of the right of self-defense. This section focuses on

when the right of self-defense is justified after an armed attack by

analyzing the immediacy issue, concluding that immediacy is not a

separate requirement, but merely one factor in interpreting the necessity

criterion. Part IV then applies that conclusion to the Cheonan incident,

ultimately concluding that the ROK government had the right of self-

defense once it identified the cause of the incident and the aggressor. In

4 In fact, an academic seminar took place in Seoul on 31 May, addressing the legal issues

regarding the Cheonan incident. At this event, Sukhyoen Kim, an international law

professor at Dankook University, argued that it was impossible to exercise the right of

self-defense when considerable time had passed after the armed attack occurred. As part

of his reasoning, he mentions the immediacy principle, arguing that the use of military

force as an exercise of the right of self-defense should occur immediately after the armed

attack. Hongsuk Ahn, It Is Necessary to Fulfill Immediacy and Necessity Criteria to

Exercise the Right of Self-Defense, YONHAPNEWS, May 31, 2010, at A1.

5 YORAM DINSTEIN, WAR, AGGRESSION AND SELF-DEFENSE 208 (4th ed. 2005).

6 See id. at 242.

7 Even though Professor Yoram Dinstein mentions immediacy as one of the requirements

in the exercise of the right of self-defense, he acknowledges two exceptions in the

immediacy principle. See infra note 79.