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When news broke that the United States had approved a revised version of its Nuclear Employment Guidance – a document updated roughly every four years – specifically to prepare for potential “coordinated nuclear challenges” from North Korea, China, and Russia, it sparked widespread media coverage both domestically and internationally. The consensus among experts featured in various media outlets is clear: the United States finds itself in a position where it must prepare for the shifting nuclear balance in the region, driven by China’s significant expansion of its nuclear capabilities and North Korea’s advancing nuclear program. Consequently, the US nuclear strategy, long focused on deterring Russia, is now pivoting to address the complex, multifaceted threats posed by China, Russia, and North Korea.

However, views diverge on how the US should respond if North Korea, China, and Russia were to coordinate military operations– whether simultaneously or sequentially – in the region. While there is no common view on how crises will evolve, there are varying views on the impact of the new guidance. Some argue for the necessity of flexible nuclear operation plans, including the redeployment of tactical nuclear weapons in the Indo-Pacific. Others express concern that in response to the nuclear modernisation efforts of China and North Korea, the United States might increase its nuclear arsenal, potentially accelerating a regional arms race and heightening regional insecurities. Due to limited information about the new guidance, there are worries that South Korea’s voice might not be sufficiently reflected in critical US decisions regarding nuclear use. As a result, there are calls for the South Korean government to clarify whether nuclear-related communications between South Korea and the United States are being conducted smoothly.

This situation raises several critical questions that warrant careful consideration. The first is whether the new guidance means a significant shift from the fundamental principles of US nuclear posture. The second is whether this change will introduce greater uncertainty into the nuclear deterrence cooperation between the United States and South Korea. The third is whether this development will necessitate South Korea pursuing its own nuclear deterrence options.

The new guidance is unlikely to deviate substantially from the overarching nuclear strategy favored by the Biden administration. It is expected to create opportunities for enhanced nuclear-conventional integration between the United States and South Korea, and, with an emphasis on tailored extended deterrence, the predictability of the alliance cooperation is likely to increase, reducing the need for South Korea to take independent action.

Continuity of the US Nuclear Strategy

The new guidance produced by the Biden administration should be viewed as an extension of the Nuclear Posture Review (NPR). The NPR is a comprehensive policy document that establishes the foundational framework for the structure and role of nuclear weapons in US national security. The Nuclear Employment Guidance provides the strategic and tactical instructions necessary to implement the principles outlined in the NPR. Given the objective of the guidance in maintaining strategic stability at a reasonable cost while hedging against vulnerabilities, it is perhaps only natural that the prioritisation of the personnel, systems, and infrastructure that comprise the nuclear triad would be reassessed in response to changing circumstances. Therefore, the new guidance is likely to focus more on how to upgrade and operate nuclear forces while adhering to the fundamental principles.

In this context, the White House has clarified that “the most recent guidance is largely based on the directives issued by the previous administration, with continuity taking precedence over change.” Given President Biden’s personal support for a no-first-use and sole-purpose policy, his administration is thought to be committed to upholding these principles. The US maintains that nuclear weapons would only be used in extreme circumstances, as stated in the NPR. Given that the Biden administration’s nuclear strategy is expected to uphold existing principles, the likelihood of redeploying tactical nuclear weapons to the Korean Peninsula or endorsing South Korea’s nuclear armament is low. Such actions would contradict the United States’ longstanding commitment to nuclear non-proliferation and maintaining a high threshold for nuclear use to ensure stability.

Enhancing Integrated Deterrence

The United States places a strong emphasis on enhancing integrated deterrence as a means of preventing nuclear crises in regional conflicts, an approach that also benefits South Korea. The United States now focuses on how to flexibly integrate conventional forces with nuclear options to address a wide range of threats, aligning with its principle of reducing reliance on nuclear weapons. The US government describes the concept of integrated deterrence as a strategic approach that combines nuclear, conventional, cyber, space, and informational capabilities to deter adversaries across multiple domains. As threats diversify, so too must the means of response, ensuring that there are numerous steps and alternatives before reaching a scenario where nuclear use becomes a consideration. Slowing the escalation of a crisis can be achieved by segmenting deterrence into finer stages, thereby building a credible and adaptable deterrence framework that utilizes the full spectrum of tools available. In this context, the NPR specifies the importance of identifying and assessing conventional capabilities that contribute to deterrence and emphasizes the need to appropriately integrate these capabilities into operational planning.

Effectively integrating nuclear and conventional means can also be achieved by leveraging the capabilities of US allies. The strategy of utilizing allied advanced conventional military power to respond to regional conflicts and limited threats, while enhancing interoperability and joint operational capabilities, has been a longstanding objective of the US. In alignment with this approach, the US established the US-ROK Nuclear Consultation Group (NCG) in 2023 and developed joint implementation measures that include nuclear-conventional integration. The US and South Korea are discussing procedures to support US strategic operations with South Korea’s conventional capabilities in a crisis, and have conducted tabletop exercises (TTX) simulating North Korean nuclear weapon use scenarios. By coordinating nuclear and conventional deterrence, the US will continue to maximize deterrence effectiveness at a lower cost by utilizing allied capabilities, suggesting that coordination efforts will continue to progress rather than regress.

Tailored Extended Deterrence

Under the new nuclear guidance, the importance of tailored extended deterrence is set to increase, potentially strengthening the US-ROK alliance. As the United States develops strategies to counter a broad spectrum of threats from not only Russia but also China and North Korea, it will need to continuously evaluate various regional crisis scenarios that these nations might generate. Given the unique security challenges on the Korean Peninsula, the United States must develop a deterrence posture that is specifically tailored to this context, necessitating close consultation and discussions on the division of roles with South Korea. As a result, the new guidance is likely to lead to greater involvement of South Korea in strategic discussions, rather than its marginalization.

However, these changes come with both positive and negative considerations. On the positive side, there will be more opportunities to enhance interoperability and readiness through strategic consultations and joint military exercises. As the United States and South Korean forces assess how effectively they can operate together, South Korea’s confidence in the US extended deterrence commitment may increase. On the downside, as the scope of US deterrence expands, South Korea may find itself more deeply involved in efforts to deter and respond to threats not just from North Korea, but also from China and Russia. This increased involvement could mean that South Korea will engage in discussions with the United States about joint responses to simultaneous or sequential nuclear and conventional threats from North Korea, China, and Russia, thereby increasing the likelihood of South Korea becoming entangled in broader regional conflicts.

South Korea’s entanglement in US deterrence strategies could strain its relationships with neighboring countries, cause trade restrictions or other forms of economic pressure, and constrain its policy options. Therefore, South Korea should carefully examine and prepare for the benefits and risks that may arise from such an expanded role.

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Image: US President Joe Biden, South Korean President Yoon Suk Yeol, US Army Commander Gen. Paul LaCamera, and Lieutenant General Sung Chun Choi at the Air Operations Center of Osan Air Base in Seoul, South Korea, 22 May 2022 (Official White House Photo by Adam Schultz).