Analysis of the ROK-U.S.-Japan Foreign Ministers’ Joint Statement: A Dual Structure of Deterrence as Justification and SMRs/Economic Security as Practical Interests

Executive Summary

The September 21 ROK-U.S.-Japan Foreign Ministers’ Joint Statement reaffirmed the commitment to the complete denuclearization of North Korea, but substantive policy progress is concentrated on the implementation track of the Memorandum of Cooperation (MOC) on Small Modular Reactors (SMRs) signed on July 7. The timing of the statement, just three days before the U.S.-China summit in Washington, suggests it was intended to preemptively solidify the alliance in preparation for the uncertainties of summit diplomacy. The North Korea track is likely to remain a statement-level reaffirmation, as the United States has already acknowledged a lack of progress and North Korea immediately reacted with hostility. In contrast, the SMR “fleet deployment” approach has entered a concrete implementation phase, combining financial, technological, and EPC (Engineering, Procurement, and Construction) capabilities. Recognizing this asymmetry, South Korea should adopt a dual approach: maintain a defensive management posture on the North Korea track while simultaneously securing a voice in the SMR implementation plan and the economic security consultative body by establishing permanent working-level channels and engaging early. While it is premature to conclude that the central axis of trilateral cooperation has completely shifted to economic security and energy, it is rational to allocate resources based on the premise of a dual structure where security provides the justification, and energy and economic security represent the practical interests.

I. Situational Analysis

Analysis of the ROK-U.S.-Japan Foreign Ministers’ Joint Statement: Expanding from North Korea Deterrence to Economic Security and Energy

1. Background and Developments

The trilateral ROK-U.S.-Japan foreign ministers' consultation was an extension of a trend already foreshadowed in the September 18 bilateral meeting in Washington between South Korean Foreign Minister Cho Hyun and U.S. Secretary of State Marco Rubio. That meeting simultaneously addressed three tracks—investment in the United States, contributions related to the Strait of Hormuz, and the North Korea issue—but failed to reach a firm conclusion on any of them [7]. Regarding U.S.-North Korea dialogue, the U.S. side merely reaffirmed its position that "there has been no concrete progress" [8]. Contributions to the Hormuz mission also remained at the level of an expression of will in principle [7]. In this context, the only track with a concrete schedule was nuclear power cooperation [7].

The substance of this nuclear power track is the Memorandum of Cooperation (MOC) on Small Modular Reactors (SMRs) signed by the three countries on July 7 [1]. This MOC established a trilateral framework to accelerate the deployment of SMR and advanced reactor technologies, primarily targeting the Indo-Pacific region [1]. The explicit goal of the memorandum is to enhance economic security by leveraging the three countries' complementary nuclear industry capabilities and to provide partner nations with high-standard civil nuclear options [1]. China's state-run media outlet, the Global Times, had been closely monitoring this trend since early September. It reported that the three countries were also pursuing the signing of a memorandum of understanding on Arctic cooperation in New York on the sidelines of the UN General Assembly, characterizing this move as one that raises "concerns of geopolitical and security competition" [13]. This demonstrates China's wariness about the diversification of trilateral cooperation beyond the scope of deterring North Korea.

2. Current Situation

On September 21 (local time), Minister Cho Hyun, Secretary Rubio, and Japanese Foreign Minister Motegi Toshimitsu met at the Lotte New York Palace Hotel in New York and agreed on a joint statement [2][5]. The statement's ostensible main point is to reaffirm a "resolute commitment" to "the complete denuclearization of North Korea in accordance with UN Security Council resolutions" and to urge North Korea to return to dialogue [2]. It also codified the intent to prohibit support for revenue-generating activities for North Korea's nuclear and ballistic missile programs [2]. Yonhap News Agency described this as a "resolute" commitment, reporting the meeting as a move by the three countries to pressure North Korea to resume dialogue [5].

The timing of this meeting is significant, as it was held three days before the U.S.-China summit. Indeed, around the same time, USTR Representative Jamieson Greer and Treasury Secretary Scott Besent met with Chinese Vice Premier He Lifeng in New York for preliminary coordination ahead of the Washington summit [6]. Representative Greer stated that the two countries were deepening their trade relationship "based on the strong relationship between President Trump and President Xi Jinping" [6]. This parallel schedule shows that the ROK-U.S.-Japan foreign ministers' meeting took place in the shadow of U.S.-China summit diplomacy. From the allies' perspective, the circumstances suggest a need to preemptively solidify a minimum foundation for trilateral cooperation, regardless of the summit's outcome.

North Korea immediately pushed back against these moves. In a September 21 statement released through the Korean Central News Agency (KCNA), a Foreign Ministry spokesperson condemned the U.S.-led "multinational sanctions monitoring team" as a "conspiratorial organization," accusing it of "openly ignoring the principles of international law, which have at their core respect for sovereignty and non-interference in internal affairs" [14]. In an earlier statement on September 18, North Korea had also criticized the International Atomic Energy Agency (IAEA) General Conference's resolution against it as an act that "takes issue with the legitimate and self-defensive exercise of sovereignty of the Democratic People's Republic of Korea" [16]. This reaction from North Korea highlights the difficulty the three countries face in getting a substantive response to their call for dialogue.

3. Key Actors and Positions

South Korea's Ministry of Foreign AffairsAmid the asymmetrical progress across the three tracks (investment, Hormuz, North Korea), the ministry is positioned to leverage the nuclear power MOC as its most concrete achievement [7]. Immediately after the Washington meeting on September 18, Minister Cho Hyun hinted at points of agreement on investment to correspondents at the South Korean embassy [8][11], and the government was scheduled to report to the National Assembly on September 22 [11]. However, there are reports that the Special Purpose Vehicle (SPV) structure, originally designed as a safeguard for principal recovery, was altered at the U.S.'s request, making the actual implementation of the investment conditions uncertain [7].

U.S. Department of State and USTRApart from the symbolic measure of reaffirming the principle of North Korea's denuclearization, they are focusing their substantive capabilities on preparations for the presidential summit. The fact that Representative Greer and Secretary Besent held a separate meeting with Vice Premier He Lifeng three days before the summit [6] demonstrates a separation of tracks within the U.S. government, with the State Department's announcement of the trilateral statement proceeding in parallel with negotiations with China by Treasury and trade officials. Secretary Rubio also appears to be managing multiple diplomatic tracks simultaneously, for instance by leaving open the possibility of contact on the Iran issue on the sidelines of the UN General Assembly [15].

Japan's Ministry of Foreign AffairsThrough Foreign Minister Motegi, the ministry participated in the trilateral statement [2], but it also appears to be aligning with the United States on separate tracks, such as the Arctic cooperation MOU mentioned by the Global Times [13]. This can be interpreted as Japan's intent to actively participate in cooperative frameworks aimed at checking China in various areas, moving beyond coordination on North Korea.

North Korea's Ministry of Foreign AffairsThe ministry continues to repeat its outright rejection of calls for denuclearization through official statements [14][16]. It adheres to a framework that defines the IAEA resolution and efforts to implement multilateral sanctions as an "infringement of sovereignty," making it seem unlikely that the trilateral call to return to dialogue will lead to the opening of a substantive channel.

China (as seen through state media)China displays a wary tone regarding the expansion of ROK-U.S.-Japan cooperation itself. The Global Times defined the Arctic cooperation initiative as "geopolitical and security competition" [13], preemptively raising concerns that trilateral cooperation is diversifying and no longer confined to the North Korea issue.

4. Key Issues

First, the joint statement's reaffirmation of denuclearization remains a surface-level agreement. North Korea's response via its statements shows no incentive for a substantive resumption of dialogue [14][16]. Second, given that the statement was released three days before the U.S.-China summit, it is possible that the trilateral meeting, under the pretext of deterring North Korea, also served to demonstrate alliance solidarity in preparation for the uncertainties of summit diplomacy. Third, the extent to which discussions on implementing the July SMR MOC were concretized during this meeting is an indicator of the substantive direction of trilateral cooperation [1]. A key point to watch going forward is whether the "fleet deployment" method and the combination of the three countries' financial, technological, and EPC capabilities, as specified in the MOC [1], can translate into tangible business opportunities for the South Korean nuclear industry and government, moving beyond the traditional cooperation framework centered on North Korea deterrence. Fourth, as the asymmetry in progress across the investment, Hormuz, and North Korea tracks persists [7], a remaining challenge for the South Korean government is to devise a strategy to counter the possibility that the United States could use perceived shortfalls in security contributions as a justification for worsening investment conditions.

II. In-Depth Analysis

In-Depth Analysis: The Structural Nature and Determining Variables of the ROK-U.S.-Japan Joint Statement

1. Analysis of Root Causes

The reason this joint statement shifted its substantive center of gravity to economic security and energy, while fronting denuclearization language, lies in the asymmetrical pace of negotiations across the three tracks. As confirmed in the September 18 ROK-U.S. foreign ministers' meeting, none of the three pillars—investment in the United States, contributions related to the Strait of Hormuz, and North Korea policy—had been finalized [7]. U.S.-North Korea dialogue ended with the U.S. side's response that "there has been no concrete progress" [8]. The Hormuz contribution did not move beyond an expression of will in principle [7]. In contrast, only nuclear power cooperation had already secured a concrete milestone with the signing of the MOC on July 7 [7][1]. The very fact that the nuclear power track was the only one with actual progress explains the statement's center of gravity, even though the foreign ministers' meeting was packaged in the familiar language of denuclearization.

A more fundamental reason lies in the timing, just three days before the U.S.-China summit in Washington. That same week, USTR Representative Greer and Treasury Secretary Besent met with Vice Premier He Lifeng in New York for preliminary summit coordination [6]. Representative Greer's public commitment to deepening trade, citing the "strong relationship between President Trump and President Xi Jinping" [6], was hardly a reassuring signal from the allies' perspective. The need to document a minimum level of alliance solidarity in advance, regardless of the summit's outcome, can be seen as the substantive motivation for convening this meeting.

2. Structural Context

In the security structure, ROK-U.S.-Japan cooperation was originally institutionalized around the single axis of North Korea deterrence. Formally, this statement does not depart from that framework. The repetition of phrases like "the complete denuclearization of North Korea in accordance with UN Security Council resolutions" and "resolute commitment" [2] shows that the basis for the legitimacy of trilateral cooperation still rests on the narrative of North Korea deterrence. However, this narrative does not guarantee substantive policy progress. Through the KCNA, North Korea condemned the U.S.-led "multinational sanctions monitoring team" as a "conspiratorial organization" [14] and pushed back against the IAEA General Conference resolution, claiming it "takes issue with the legitimate and self-defensive exercise of sovereignty" [16]. This dynamic, where a statement calling for a return to dialogue coexists with North Korea's immediate rejection, is not new. It reaffirms the structural limitation that on the security track, what the three countries can actually agree on is the wording of deterrence commitments, not a change in North Korea's behavior.

In the economic security structure, U.S. efforts to secure multilateral enforcement power are proceeding separately. The USTR's convening of some 50 trading partners in September for an enforcement drill on the ban on forced labor imports [3] suggests that supply chain management is being institutionalized on a much broader scale, beyond the trilateral ROK-U.S.-Japan framework. The economic security language in the joint statement should be read as part of this U.S.-led trend of multilateral norm-setting; it is less a unique invention of the three countries and more a regional version of a larger framework being built by Washington.

In the energy structure, the key element is the "fleet deployment" method stipulated in the July 7 MOC [1]. This document specifies that the three countries will combine their financial, reactor technology, and engineering and construction capabilities to "promote industry-led projects to deploy multiple reactors" [1]. The purpose is to "lower the risks of project development, reduce costs, promote private investment, streamline licensing, and accelerate the speed of delivery" [1]. This signifies a structural shift away from country-to-country nuclear export contracts and toward a model where the three countries act as a single supply package. Although a clause states that partner countries can "select technology suppliers and project partners with full sovereignty" [1], this sovereignty clause is largely rhetorical, as the choices will in practice be structured within the industrial ecosystems of the United States, Japan, and South Korea.

3. Historical Precedents and Comparison with Similar Cases

This pattern of ROK-U.S.-Japan cooperation expanding from the single axis of security to include economics and energy is not new. After the 2023 Camp David Summit, the three countries institutionalized initiatives such as a supply chain early warning system and cooperation on critical minerals. The recent SMR MOC and joint statement can be seen as an extension of this trend, applying the same logic to the new domain of nuclear energy. The difference, however, is that this time a clear external pressure variable—the U.S.-China summit—determined the timing. Whereas the Camp David accords were reached in a relatively stable external environment, this statement has a more defensive character, having been convened amid the uncertainties of summit diplomacy.

In the context of nuclear power export competition, precedents have been set by Russia's Rosatom and the China National Nuclear Corporation (CNNC), which have already established a nuclear export model in Asia, Africa, and Latin America that combines government-to-government financial packages. The ROK-U.S.-Japan "fleet deployment" concept [1] has the character of a belated response to this model. The fact that the United States lost its competitiveness in exporting commercial reactors on its own long ago is also a reason why it needs to combine Japan's engineering and construction capabilities with South Korea's track record in nuclear plant construction. The experience of Korea Hydro & Nuclear Power (KHNP) in building the Barakah nuclear power plant in the United Arab Emirates is highly likely to be utilized as a tangible asset in this initiative.

The framework for responding to economic coercion also has precedents. Experiences with China's weaponization of resources, such as the 2010 rare earth export restrictions and the urea solution crisis in the 2020s, became the direct motivation for establishing the trilateral supply chain early warning system. The fact that this statement targets "non-market practices" and "arbitrary export restrictions" is the institutional result of these learned lessons.

4. Key Variables Shaping Future Developments

The biggest variable is the outcome of the U.S.-China summit in Washington, set to take place in three days. As Representative Greer has already mentioned "optimizing trade in non-sensitive goods" and "improving market access for American farmers, manufacturers, and workers" [6], the possibility cannot be ruled out that any agreement reached at the summit could include content that conflicts with allies' interests in the areas of tariffs and export controls. In that case, the economic security commitments in the ROK-U.S.-Japan joint statement would be assessed as having served a more symbolic reassurance function than having substantive binding force. Conversely, if the summit yields more limited results than expected, the trilateral economic security consultative body and the SMR implementation plan could quickly gain traction as tangible tools for checking China.

The second variable is the speed at which the SMR implementation plan is concretized. The MOC presented "technical support for feasibility studies and regulatory development, and support for mobilizing finance and investment" as its implementation strategy [1], but the viability of this initiative will depend on when and in what form actual contracts are won for specific reactor types in specific countries. Since nuclear power projects typically take years just for licensing and financing, there is a risk that the "fleet deployment" concept could remain a paper framework if no tangible results are produced within the current administration's term.

The third variable is North Korea's response. As the KCNA has already shown a hardline reaction to the multinational sanctions monitoring team and the IAEA resolution [14][16], it is unlikely that the trilateral call to return to dialogue will lead to actual contact. However, if the intensity of North Korea's backlash escalates, it would create an incentive for the focus of ROK-U.S.-Japan cooperation to revert to security deterrence. In that case, the political priority of the economic security and energy tracks could be relatively diminished.

The fourth variable is political acceptability within South Korea. It has already been pointed out that there are signs that investment in the United States, contributions related to the Strait of Hormuz, and nuclear power cooperation are effectively tied together as a single negotiation package [7]. How the speed and conditions of the nuclear MOC's implementation are handled in the process of reporting to the National Assembly and undergoing public scrutiny will determine the amount of political capital the South Korean government can invest in this initiative.