At the end of April, Yoon Suk-yeol — the first president of the Republic of Korea to pay a state visit to the United States in the past 12 years — met with U.S. President Joe Biden. The highlight of the visit was a declaration on strengthening the U.S. commitment to ROK security under the doctrine of extended deterrence — which includes nuclear weapons.
The U.S. and the ROK will establish a new consultation team to discuss nuclear and strategic planning and upgrade nuclear deterrence in joint military exercises. The U.S. will dispatch nuclear-capable submarines to visit the ROK, which Yoon said would mitigate concerns about nuclear threats from the Democratic People’s Republic of Korea.
While the approach is different from NATO’s nuclear collective defense — as the U.S. has no plan to deploy nuclear weapons in South Korea — the ROK’s participation in U.S. decision-making on nuclear deterrence signals an evolution toward a quasi-NATO arrangement.
Meanwhile, the joint statement issued by the countries’ leaders commemorating the 70th anniversary of the U.S.-ROK alliance defined the alliance as the bedrock for peace and prosperity in the Indo-Pacific, including the matter of Taiwan. Also, the ROK committed to host the third Summit for Democracy. Thus the U.S.-ROK alliance seems to have begun turning from a focus solely on the Korean Peninsula to NATO-style security thinking —collective defense — when its comes to regional security hot spots.
But instead of providing further security guarantees for the ROK, the increased visibility and transparency of extended deterrence would further escalate tensions in Northeast Asia, resulting in greater insecurity for all parties. The main reasons for the ROK’s request for the U.S. to enhance extended deterrence include doubts over a previously promised U.S. nuclear umbrella — whether it would continue to be valid with the North achieving unprecedented nuclear and missile capabilities that could threaten the continental United States. There have also been voices within the ROK for developing nuclear capabilities.
To ensure that extended nuclear deterrence by the United States continues to be reliable, Seoul wanted the U.S. to demonstrate its resolve to protect the ROK in two aspects: first to show capabilities for a nuclear strike and second to allow the ROK to participate in the process of nuclear decision-making.
On the surface, the U.S. has met all of the ROK’s demands, yet there has been no change in the nature of the U.S.-ROK relationship. The U.S. sending nuclear-capable submarines appears to be a demonstration of its resolve based on nuclear deterrence, but the advantages of nuclear-powered submarines lie in their stealth and long-distance attack ability, so militarily this makes little sense. It’s mainly a political signal.
In Pyongyang’s eyes, however, frequent visits of nuclear-capable submarines are provocative. The U.S. decision-making power on the use of nuclear weapons falls ultimately in the hands of the U.S. president. The highly centralized nature of U.S. nuclear decision-making means autonomy will not be shared with allies, as doing so would greatly reduce the effectiveness of nuclear weapons as a diplomatic tool.
Although the U.S. pledged to enhance intelligence sharing and to increase the frequency of consultation, it is unthinkable the U.S. would be willing to sacrifice its dominance and autonomy on nuclear issues. On the contrary, the two countries’ joint military drills and scenario planning — all aimed at increasing nuclear deterrence — will add to tensions in the region.
Meanwhile, the NATO-style security outlook under which security issues are seen as universally connected is beginning to gain traction in the ROK. The regionalization of the U.S.-ROK alliance seems to have satisfied Seoul’s dream of becoming a diplomatic powerhouse. But binding itself to the war chariot suggests that its diplomatic space is narrowing, not widening. If the ROK’s foremost expectation for the summit is the enhancement of extended deterrence, the U.S. will get what it wanted, with Seoul taking sides in international politics.
This is reflected on the Ukraine issue, as the U.S. hopes Seoul will provide Ukraine with weapons and ammunition. This would show a connection between European and Asian security, as key East Asian ally would be demonstrating a conspicuous consensus on strengthening America’s global alliance system.
The ROK has yet to provide weapons to Ukraine, but judging from the joint statement the space for ROK-Russia relations has been greatly restricted. At the same time, the ROK’s statement that the issue of Taiwan and the Korean Peninsula are both global meets the U.S. need for building integrated deterrence capabilities in the region.
The rapid warming of Japan-ROK relations is also based on assumptions of multiple security challenges in the region. Voices for a quasi-trilateral U.S./Japan/ROK alliance are also on the rise, which deals a heavy blow to the ROK’s relationship with China. The U.S. has praised its relationship with the ROK as a global, comprehensive strategic alliance, and President Yoon has been invited to participate in the Hiroshima summit of G7 leaders, which appears to conform with the ROK leader’s vision of turning his country into a “fulcrum” in the international community. However, if the ROK doesn’t build mutual trust with China and Russia, its two largest neighbors — and especially with China as its largest economic partner — such a vision borders on fantasy.
In essence, the enhancement of nuclear extended deterrence by the U.S. and ROK and the tendency to regionalize the U.S.-ROK alliance illustrate the spread NATO-style security thinking. From China’s perspective, this could change the status quo of the security framework of the entire Northeast Asian region, which will result in a further imbalance in the region’s security order. The trend, therefore, requires resolute opposition so that the notion of collective defense being effective will not run riot in the area.
In the meantime, China should accelerate a new round of economic and social integration in East Asia, including Northeast Asia, to counter the concept of integrated military deterrence.
