The enduring U.S.-Republic of Korea security alliance has effectively deterred conflict and preserved peace on the Korean Peninsula for over 63 years. In today’s context, characterized by the escalating threat posed by a nuclear-armed and aggressive North Korea, increasing tensions in U.S.-China relations, and rapidly evolving security dynamics in the Asia-Pacific region, the significance of the U.S.-ROK security alliance has reached new heights. It is a crucial cornerstone of America’s ability to project military strength, navigate uncertainty, and uphold stability in an area of utmost importance to U.S. interests.

The alliance between the United States and South Korea has been robust since the signing of the Mutual Defense Treaty in 1953. This treaty establishes mutual defense assistance in the event of an armed attack against either party.

Over the years, the alliance has expanded to include joint military exercises, operations, and regular coordinated consultations to address regional security issues. Tensions on the Korean Peninsula have recently increased due to North Korea’s ongoing nuclear and missile tests and hostile rhetoric. In retaliation, the US has kept a noticeable military presence in South Korea, including sporadic submarine deployments. These deployments demonstrate the U.S. commitment to South Korea’s security and the upkeep of regional stability, sending a strategic message to North Korea and its allies.

In a significant move, the United States has recently deployed a nuclear-armed ballistic missile submarine (SSBN) to South Korea. This deployment marks the first time since the 1980s that such a sub has been sent to the region. The decision comes as both countries engage in talks to enhance coordination and prepare for potential scenarios involving a nuclear conflict with North Korea.

White House Indo-Pacific coordinator Kurt Campbell announced the submarine’s visit on Tuesday. The deployment was anticipated following a joint declaration made during a summit between South Korean President Yoon Suk-yeol and US President Joe Biden in Washington, DC, back in April.

By deploying a nuclear-armed submarine to South Korea, the United States aims to demonstrate its commitment to its ally’s security and strengthen coordination in addressing the North Korean nuclear threat. This move underscores the significance both countries place on maintaining a strong deterrent against potential aggression from North Korea and the importance of close collaboration in addressing regional security challenges as part of the agreements reached in April between the presidents of the United States and South Korea to address North Korea’s increasing nuclear threat, periodic visits by US SSBNs to South Korea were established. Additionally, the two countries agreed to establish a bilateral NCG (nuclear consultative group) and expand military exercises. The recent visit of the nuclear-armed submarine to South Korea demonstrated the United States’ commitment to implementing its “extended deterrence” pledge. This commitment entails the US utilizing its full range of military capabilities, including nuclear weapons, to protect its allies. The South Korean Ministry of Defense emphasized that the visit signifies the allies’ strong ability and preparedness against North Korea.

The United States and South Korea aim to deter any potential aggression from North Korea by reaffirming their commitment to extended deterrence and showcasing their military posture. These actions underscore the importance of maintaining a robust defense alliance and sending a clear message regarding the consequences of North Korea’s nuclear provocations.

During the Cold War, the United States had a continuous military presence in South Korea to discourage any potential acts of aggression from North Korea. As part of this presence, submarines regularly patrol the waters surrounding the Korean Peninsula to monitor North Korean naval activities. In 1994, a significant agreement known as the Agreed Framework was reached between the United States and North Korea. The primary objective of this agreement was to address concerns regarding North Korea’s nuclear program. Under the terms of the deal, North Korea committed to freezing and ultimately dismantling its nuclear weapons program. In return, the United States pledged to provide economic assistance and support in constructing civilian nuclear reactors.

The Agreed Framework represented a diplomatic effort to mitigate tensions and promote regional stability by curbing North Korea’s nuclear ambitions. The presence of U.S. submarines during the Cold War and the subsequent agreement in 1994 reflected the ongoing commitment of the United States to maintain security in South Korea and address the nuclear threat posed by North Korea.

North Korea’s pursuit of nuclear weapons has gained heightened significance due to its recent threats of nuclear weapon use in conflicts and a series of missile tests, totaling approximately 100 since the beginning of the previous year. North Korea has a numerical edge over the ROK in terms of soldiers, tanks, artillery, and aircraft, despite the ROK having a technological edge, more robust training programs, and contemporary equipment. Most North Korean forces are in a forward position close to the demilitarized zone, allowing them to attack the South rapidly and effectively in the event of a confrontation.

The Korean People’s Army (KPA) can reach the capital of South Korea and a sizable chunk of its populace with long-range artillery and tactical rockets. North Korea’s recent test of a more advanced intercontinental ballistic missile capable of reaching the mainland United States was of particular concern. Following the launch, North Korean leader Kim Jong Un stated that his country’s nuclear combat capabilities had been further strengthened.

In response to these developments, President Joe Biden, during his summit with South Korean President Yoon Suk-year in April, also warned about North Korea’s nuclear activities. The meeting resulted in both leaders acknowledging the integral role of the NCG (nuclear consultative group) in facilitating discussions and advancing bilateral approaches, including guidelines, for nuclear and strategic planning and responses to North Korean aggression.

The evolving nuclear ambitions of North Korea have prompted heightened concern and the need for close coordination between the United States and South Korea.

Both countries recognize the importance of effective strategic planning and responses to address North Korean provocations and safeguard regional security. The establishment and activation of the NCG serve as mechanisms for strengthening collaboration and ensuring a coordinated approach in dealing with North Korea’s nuclear threats.

Kim Yo Jong, a senior adviser and powerful sister of North Korean leader Kim Jong Un, issued a statement on Monday expressing concern over the United States’ efforts to strengthen its extended deterrence commitment to South Korea. Kim Yo Jong warned that these actions by the US would push North Korea further away from the desired negotiating table and prompt them to enhance their military capabilities. Kim Yo Jong emphasized that North Korea is prepared to respond strongly to any actions that violate its sovereignty and territorial integrity. She urged the US to refrain from provocative acts jeopardizing North Korea’s security, describing such actions as foolish.

The statement from Kim Yo Jong highlights North Korea’s discontent with the US reinforcement of its deterrence posture. It suggests that it could have adverse implications for future negotiations. The language used underscores North Korea’s commitment to safeguarding its national security and sends a clear message regarding the consequences of provocative actions by the United States.

Nurturing and enhancing the alliance relationship, which has proven beneficial for U.S. interests, will be a primary responsibility for the U.S. This task gains even more significance given the mounting concerns within the region regarding the long-term commitment of the United States, apprehensions about emerging isolationist tendencies in the country, and anxieties surrounding China’s aspirations to establish dominance in the area. During a cabinet meeting, Yoon emphasized the significance of establishing a consultative group, highlighting its role in creating a robust and efficient extended deterrence between South Korea and the United States. He further emphasized that their alliance has undergone an upgrade, now operating under a new nuclear-focused framework. Campbell and Kim Tae-hyo, South Korean Deputy National Security Director, jointly chaired the meeting.

In April, the agreements reached between Biden and Yoon drew condemnation from North Korea, who interpreted them as a demonstration of the allies’ intense hostility towards their nation. As a form of protest, North Korea threatened to escalate its nuclear utilization doctrine even further.