On the night of March 26, the South Korean Navy corvette Cheonan on patrol operation sank off the west coast of the Korean Peninsula in the Yellow Sea. The ship was split in half, and 46 South Korean sailors ultimately lost their lives. The South Korean government immediately salvaged the sunken ship and launched an international investigation team to determine the cause of the sinking. After examining fragments collected from the wreckage, the investigation team reached the conclusion that the Cheonan sunk not because of an internal explosion but because of a torpedo fired by a North Korean submarine. The South Korean government declared this incident a “grave national security issue” and that it will make North Korea pay. The international community also saw this provocation as a severe violation of international law and similarly emphasized an “appropriate” response to the incident.
The Republic of Korea (ROK) and the United States are allies that signed the Mutual Defense Treaty. The primary mission of the Mutual Defense Treaty is to prevent war and maintain peace and stability on the Korean Peninsula. The experience from the past sixty years shows that this security alliance has successfully served its purpose. For the U.S., it has effectively dissuaded and deterred North Korea from taking overt military actions on the Korean Peninsula by providing the ROK with “extended deterrence, including the nuclear umbrella” and displaying its overwhelming military force and political will to defend its ally from the North’s aggression. The ROK, confident in U.S. extended deterrence and security commitment to its defense, has also been assured of its security and has believed that the deterrence would hold effective. Such belief has been affirmed as the relative peace and status quo on the Korean Peninsula has lasted over the past sixty years.