Time to turn ROK-US agreement into action

As the first anniversary of the ROK–U.S. Joint Fact Sheet singed in November 2025 approaches, Seoul and Washington should demonstrate concrete progress in implementing their commitments. The United States approved South Korea’s construction of nuclear-powered submarines and pledged close cooperation on the requirements for the program, including avenues to source fuel. Those political commitments must now be translated into clear timelines and clearly assigned responsibilities.

Securing a shipyard alone will not deliver a nuclear-powered submarine. Fuel specifications and supply arrangements must be established to align reactor design and testing, submarine construction and entry into service. Delays in fuel cooperation could lead to design changes, higher costs and uncertainty for companies considering investment. Diplomatic negotiations and domestic development must not become trapped in a cycle in which each waits for decisions from the other.

There has been some progress. In December 2025, the two countries’ foreign affairs officials agreed on the need to move promptly toward follow-up consultations on nuclear cooperation, shipbuilding and nuclear-powered submarines. At a congressional hearing in March, a senior State Department official explained that an interagency review was underway, with the Pentagon addressing infrastructure issues and the State Department handling matters related to potential nuclear fuel provision.

In June, delegations from both countries met in Seoul for follow-up consultations on nuclear-powered submarines and civil nuclear cooperation. They agreed to pursue tangible results promptly and establish a mechanism to review progress. In September, it was also confirmed that South Korea had formally notified the International Atomic Energy Agency (IAEA) of its intention to begin consultations on an arrangement under Article 14 of its Comprehensive Safeguards Agreement. This is an important step toward developing naval nuclear propulsion while upholding nonproliferation obligations. However, according to an Oct. 30 news report, a senior South Korean presidential official said that follow-up security negotiations remained on hold and that a second round had yet to be scheduled. Beginning consultations does not, by itself, guarantee sustained progress.

Procedural progress must also be distinguished from securing fuel. The Joint Fact Sheet did not guarantee direct U.S. fuel supply or delivery by a specified date. Nor do consultations with the IAEA determine the supplier or delivery schedule. The government nevertheless has a responsibility to explain what has been agreed and which decisions remain outstanding.

The most immediate reason South Korea needs nuclear-powered submarines is the threat posed by North Korea’s submarine-launched ballistic missiles. Because the movements of North Korean submarines and the timing of a potential launch cannot be predicted with certainty, the ability to maintain prolonged underwater surveillance and tracking is essential. Nuclear-powered submarines offer advantages in submerged endurance and sustained high-speed operations. Their effectiveness increases when they operate alongside surface ships, maritime patrol aircraft and underwater surveillance systems.

South Korea must also prepare for neighboring countries’ expanding submarine forces and maritime influence. Protecting sea lines of communication and maritime interests, while strengthening the persistence of combined ROK–U.S. anti-submarine warfare operations, serves both allies. A greater South Korean contribution to surveillance and anti-submarine warfare in surrounding waters would also give the U.S. Navy greater operational flexibility. The missions of South Korean nuclear-powered submarines should, however, be grounded in the defense of the Korean Peninsula and South Korea’s sovereign authority over decisions concerning their employment.

For more than seven decades, the ROK–U.S. alliance has remained one of the world’s strongest. South Korea’s submarine construction expertise and naval maintenance capabilities are valuable assets for the United States as well. Nuclear fuel cooperation and shipbuilding cooperation should not be treated as a simple exchange of concessions. The case should instead be made clearly that both can strengthen the alliance’s maritime security and industrial base.

It is time to put specific negotiating objectives in writing. A framework should identify the supplier, uranium enrichment level and fuel form, the timing of initial delivery, ownership arrangements and principles for managing spent nuclear fuel. Both governments should also identify the U.S. laws and congressional review procedures applicable to the particular materials or technology to be transferred. Civil nuclear enrichment and reprocessing cooperation and fuel cooperation for naval propulsion serve different purposes and follow different legal pathways. Each therefore requires a clearly defined negotiating agenda.

Regardless of the outcome of the U.S. midterm elections, engagement between South Korea’s National Assembly and the U.S. Congress must deepen. Reliable implementation of executive-level agreements requires understanding and support across party lines. Lawmakers from South Korea’s governing and opposition parties should jointly engage the relevant House and Senate committees and key members of Congress. They should explain the military requirement, the benefits to the alliance, the proposed use of low-enriched uranium and the measures intended to uphold nonproliferation commitments.

Parliamentary diplomacy must go beyond goodwill visits. South Korean representatives should provide evidence-based answers to congressional questions about fuel management, technology protection, financial responsibilities and the industrial benefits for members’ states and districts. The National Assembly should support the government’s negotiations while scrutinizing budgets, schedules and safety arrangements. Bipartisan support should be accompanied by responsible oversight that helps sustain the program.

South Korea must also strengthen its domestic arrangements for implementing the program. The Ministry of Foreign Affairs should lead diplomatic negotiations with Washington, while the Ministry of National Defense and the Defense Acquisition Program Administration define operational requirements and acquisition schedules. Nuclear research institutions and industry should specify the scope of development and technical requirements, and safety regulators should participate from the outset. A governmentwide coordination mechanism must make clear who is responsible for each decision and when it must be made, so that negotiated outcomes can be translated promptly into program execution.

Preparations that can proceed should advance while fuel decisions remain pending. Defining operational performance requirements, securing design personnel and preparing testing and maintenance infrastructure should move forward in parallel, with careful management of the risk that fuel decisions may require changes. The government should work backward from the design and construction schedule to set negotiating milestones and prepare contingencies for delays. It should report regularly to the National Assembly on progress and major risks, using closed briefings for sensitive matters.

Alliance credibility is demonstrated through implementation. South Korea must prepare for responsible development and effective nonproliferation arrangements, while the United States should clarify the practical pathways for fulfilling its commitments. Legislators in both countries should support this work across election cycles and changes of government. As the agreement’s first anniversary approaches, Seoul and Washington need an implementation plan that places fuel procurement and construction preparations on a single, coordinated timeline.

Ret. Navy Capt. Moon Keun-sik is distinguished professor of Graduate School of Public Policy at Hanyang University in Seoul.