Against the backdrop of increased Chinese aggression, and in parallel with the United States, Japan, and many Western nations, the Republic of Korea (ROK) is beginning to publicly voice its concerns about the potential for a military contingency in the Taiwan Strait. Accordingly, Seoul is stepping up its level of engagement with Washington, Taipei, and other like-minded partners. Beginning with high-level statements in 2021 such as the unprecedented US-ROK Leaders’ Joint Statement, which emphasized for the first time the two governments’ concerns about “the importance of preserving peace and stability in the Taiwan Strait,” Seoul has been gradually signaling a potential rethink in its approach to regional security issues—and by extension, the Taiwan Strait.
While current trends in Seoul’s strategic rethinking predate the current presidential administration, the realignment between Seoul and other like-minded partners began in earnest in May 2022 with the election of Yoon Suk Yeol as the country’s president. The new Korean president’s vision, which he laid out during the presidential campaign, strategically aligns the ROK’s national security interests on the US-ROK treaty alliance with the country’s shared democratic values and interests with neighboring countries like Japan.
Seoul’s transformative stance—which includes subtle changes in its approach to Taiwan—has helped to create the conditions for the United States to make headway in its longstanding effort to network its treaty alliances in East Asia, as demonstrated by the historic Camp David summit between the leaders of the United States, Japan, and South Korea. Ancillary to its treaty commitments and the shifting regional security situation, Seoul has also been enhancing engagement with Taiwan, which has taken on three forms: high-level statements, parliamentary diplomacy, and upgraded Track 1.5 diplomacy.
A year later after the landmark US-ROK leaders’ summit in May 2022, President Joseph Biden and newly-elected President Yoon released a joint statement, which went further than the prior joint statement between the two governments. The new document stated that: “The two Presidents reiterate the importance of preserving peace and stability in the Taiwan Strait as an essential element in security and prosperity in the Indo-Pacific region” [emphasis added].
That same month, while explaining his rationale for the earlier statement, President Yoon stated: “Because during the previous administration, the Taiwan issue didn’t come to the fore, so maybe it wasn’t necessary to make that clear. But Taiwan is under a lot of focus right now as an international issue. And, in this sense, I think declaring the universal principle of international law is something that contributes to the peace and prosperity of the region.”
In another interview conducted in April 2023, Yoon went even further: “After all, these tensions occurred because of the attempts to change the status quo by force, and we together with the international community absolutely oppose such a change […] The Taiwan issue is not simply an issue between China and Taiwan but, like the issue of North Korea, it is a global issue.” These statements by the Korean president reflect the continued and sustained high-level attention paid to peace and stability in the Taiwan Strait.
In the absence of formal diplomatic relations between the Republic of China (Taiwan) and the ROK, Seoul has also been stepping up its parliamentary diplomacy with Taipei in addition to these presidential statements. In late December 2022, Chung Woo-taik, the ROK’s deputy assembly speaker, and other members of the ROK National Assembly including Cho Kyoung-tae—who serves as chairman of the Korea-Taiwan Parliamentarian Friendship Association (韓台議員親善協會)—visited Taiwan. Like the United States, and many other Western nations as well as Japan in recent years, the deputy assembly speaker’s visit followed similar visits led by speakers and leaders of parliaments from other democracies in recent years—such as the United States, Czech Republic, and the vice president of the European Parliament, among others.
While still relatively low-profile, there has also been a perceptible uptick in military exchanges between retired senior military officers in Taiwan and South Korea. As the last remaining diplomatic partner in Asia to sever official relations with Taipei in 1992, Taipei and Seoul enjoyed a 40-year-old military officer exchange program that began in 1974 with three officers being trained in the ROK on a yearly basis with an unidentified number of Korean military officers receiving training in Taiwan, including military officers studying in Taiwan’s political warfare colleges.  In fact, reflecting the longstanding mil-to-mil ties between Taiwan and South Korea, it was not until 2011 that the People’s Republic of China (PRC) managed to force Seoul to sever most of its military ties with Taipei in exchange for setting up reciprocal programs with the People’s Liberation Army. In the mid-2010s, these ties between Seoul and Taipei appeared to slowly re-emerge in lower-profile forms.
For instance, in 2018, General (ret.) Lee Changhyung, a senior advisor to the ROK’s military former chief of staff under Moon Jae-in, visited Taiwan. This visit was hailed in the Taiwanese media as the first reported resumption of military exchanges between the two sides since the severing of diplomatic relations. More recently in May 2023, Park In-ho, former chief of staff of the ROK Air Force and an advisory member of the Korean Institute of Defense Analyses (KIDA), also visited Taiwan and conducted exchanges with the MND-sponsored Institute for National Defense and Security Research (國防安全研究院). In August 2023, in conjunction with a US-based Atlantic Council delegation led by former Secretary of Defense Mark Esper, the former Chairman of the Republic of Korea Joint Chiefs of Staff Admiral (ret.) Choi Yoon-hee also visited Taiwan for a round of exchanges with senior Taiwanese officials.
In a further sign of the rethinking within Seoul about its relationship with Taipei, in late 2022 the Yoon administration was reportedly considering sending a former ROK Army chief of staff and minister of defense, General (ret.) Kim Yong-woo, to serve as the representative of the country’s de facto embassy in Taiwan. However, it was confirmed in November 2022 that Seoul had pulled the plug on that idea. In February 2023, it was announced that Lee Eun-ho, who served as former director of the Korean Security Agency of Trade and Industry, would be the new representative to Taiwan. The new director may have been selected to deepen the “Chip 4 alliance” (between the United States, Japan, South Korea, and Taiwan) and coordination in semiconductor supply chain issues.
The ROK’s Role in a Taiwan Contingency
In September 2022, United States Forces Korea (USFK) Commander General Paul LaCamera revealed that USFK commanders do “contingency planning” for “anything.” In an interview with Radio Free Asia, General (ret.) Robert Abrams, the former commander from 2018 to 2021, further explained that the United States will keep open “all options” in deciding what forces might be used in the event of a military conflict between China and Taiwan, “including those assigned to the USFK.”
While the defense community in Seoul remains laser-focused on North Korea, the emergence of a more strategically flexible posture towards Taiwan in the ROK is likely related in part to the backdrop of increased cooperation between Beijing, Moscow, and Pyongyang. Indeed, the risks of a contingency over Taiwan, in tandem with a simultaneous crisis on the Korean peninsula, are increasingly in the minds of the strategic communities across like-minded capitals.
In highlighting the cause of this apparent shift in the perspectives of the ROK national security community, Sungmin Cho, a professor at the Daniel K. Inouye Asia-Pacific Center for Security Studies (APCSS), noted clearly that “there is a new reality that we are facing that [a] Taiwan contingency and contingency on the Korean peninsula are increasingly linked. That was not the case before.”
Further underscoring Seoul’s growing concerns about the Taiwan Strait, according to a Taipei Times report, former South Korean Ministry of Foreign Affairs official Lee Yong-jun stated, that, in the event of a war: “In that scenario, it would be very difficult for South Korea to only provide humanitarian aid to Taiwan, as it did during the Ukrainian war, or to remain on the sidelines […] US troops stationed in South Korea may be transferred to the Taiwan front at that time, and North Korea may be incited to take military action.” Lee concluded that Seoul would not escape the possible diplomatic, military, and economic repercussions of the war.
Putting a finer point to Seoul’s growing concerns and Korea’s evolving perspective on the security situation in the Taiwan Strait and its implications for South Korea, Han Suk-hee, president of the Institute for National Security Strategy, stated at a public forum in the United States in June 2023:
“From Korea’s perspective, Taiwan’s contingency is Korea’s contingency because Taiwan contingency includes economic containment. Eighty percent of our importation of energy goes through the Taiwan Strait. So, if anything were to happen in the strait, we would be directly affected […] [f]rom the Korean perspective Taiwan contingency is very important to our security. Secondly, if there was anything to happen in the Taiwan Strait, US forces will intervene. In that case, China declared that it would launch missiles onto US bases in Korea. So, that would cause a natural or some automatic involvement of the Korean military in the Taiwan Strait crisis.”
South Korean Public Opinion on a Taiwan Contingency
In addition to the policy elites, the South Korean public is also increasingly concerned about a military contingency in the Taiwan Strait. According to a survey conducted by the Joong-Ang Ilbo and the East Asia Institute in August, 64.5 percent of South Korean respondents agreed that South Korea should provide direct or indirect support for US military operations in a Taiwan contingency, and only 18 percent of respondents opposed any involvement of South Korea in a Taiwan contingency. Of those who supported South Korean involvement, 22.5 percent said they would support its participation in the joint military operation with the US forces, whereas 42 percent responded that South Korea’s military role should be limited to providing rear-area support for US forces. 
Ancillary to its treaty commitments with the United States, Seoul has been enhancing engagement with Taiwan. While Taipei and Seoul are enhancing their engagements, the two sides are still keeping direct talks between the two nations quiet. Even with Washington, Seoul’s official position has been that South Korea has had no discussion with US Forces Korea (USFK) or the US government about ROK’s role in a Taiwan contingency. Yet, according to Victor Cha, senior vice president for Asia and Korea Chair at CSIS who served in the National Security Council during the Bush Administration, “[M]y sense is that President Yoon is even more forward-leaning on these issues [related to Taiwan] than his bureaucracy is […] it is inconceivable to me at least that they’re [US-South Korea] not having conversations about it [a Taiwan contingency].”
The main point: In line with increasing regional concerns over cross-Strait tensions, Seoul has shown increasing willingness to align with the positions of the United States, Japan, and Western nations in expressing support for preserving “peace and stability” in the Taiwan Strait. Seoul has also displayed an increased willingness to engage with Taiwan in three areas: high-level statements, parliamentary diplomacy, and upgraded Track 1.5 diplomacy.
 As a testament of the longstanding mil-to-mil ties between Taiwan and South Korea, Seoul reportedly has had active-duty military officers posted in Taiwan. Senior military officers like General (ret.) Kim Dong-myeong (金東明) is the current president of the Alishan Association (阿里山會)—a group composed of Korean military officers who had previously trained and served in Taiwan. Kim graduated from Taiwan’s National Defense University and served previously as a defense attaché in the Republic of China (Taiwan) from 1988-1991 when the two countries maintained official diplomatic relations.
 Fleshing out what ‘rear-area support’ could include, APCSS Professor Cho explained, “for example, through base access, provision of ammunition, noncombatant evacuation and noncombat operations such as maintenance of weapon systems and augmentation of US reconnaissance capabilities.”
The author would like to thank GTI Program Associate Will Kielm for his research assistance.
Correction: An earlier version of this brief incorrectly referred to Lee Changhyung as the ROK military’s chief of staff under Moon Jae-in.