US Secretary of State Marco Rubio, Japanese Foreign Minister Motegi Toshimitsu and South Korean Foreign Minister Cho Hyun convened on the sidelines of the UN General Assembly's high-level week in New York on 21 September 2026, agreeing to intensify trilateral cooperation across artificial intelligence, semiconductors, quantum technology and critical supply chains while reinforcing the three nations' joint security posture in the Indo-Pacific. A joint statement from the US State Department confirmed the breadth of commitments, spanning economic security, emerging technology, energy resilience and North Korea's nuclear threat.

North Korea Denuclearisation and Sanctions Pressure

The three foreign ministers reaffirmed their shared commitment to the complete denuclearisation of North Korea and called on Pyongyang to return to dialogue. They pledged to strengthen coordination against North Korea's nuclear and ballistic missile programmes, cyber operations and revenue-generation activities that allegedly violate UN Security Council resolutions.

The ministers welcomed the work of the Multilateral Sanctions Monitoring Team in documenting alleged violations and sanctions evasion. They also cited a multi-country alert regarding North Korean IT workers reportedly deployed abroad under false identities to funnel earnings back to sanctioned programmes — a practice Western governments have repeatedly flagged at the UN.

The path to dialogue with Pyongyang was described as remaining open. The statement also renewed calls for resolution of cases involving abductees, detainees, unrepatriated prisoners of war and families separated by the division of the Korean Peninsula.

Economic Security and Supply-Chain Resilience

Economic security formed a major pillar of the trilateral talks. The ministers collectively opposed economic coercion, market-distorting practices and arbitrary export restrictions that disrupt international supply chains — language widely read as directed at China, though Beijing was not named in the statement.

The three governments agreed to strengthen a trilateral early-warning system designed to flag emerging supply-chain disruptions before they escalate. They also announced a new economic security consultation mechanism to coordinate responses across the three capitals.

Energy Resilience and Small Modular Reactors

The officials underscored the need to build regional energy resilience through expanded oil stockpiles and tighter cooperation between energy-producing and energy-consuming nations. They welcomed Japan's 'POWERR Asia' initiative and South Korea's push to broaden regional energy-security cooperation.

Notably, the three governments confirmed they would implement a July memorandum to accelerate deployment of small modular nuclear reactors (SMRs) in partner countries, stipulating that all such projects must adhere to high standards of nuclear safety, security and non-proliferation.

Emerging Technology: AI, Quantum and Semiconductors

On the technology front, the ministers committed to strengthening advanced-technology systems and making supply chains more resilient. Priority areas identified included artificial intelligence, quantum technology, digital infrastructure and biotechnology. They backed greater semiconductor cooperation and called for closer links between their respective national laboratories — a step that goes beyond existing bilateral frameworks.

Security Posture, Taiwan Strait and Indo-Pacific Stability

The ministers reaffirmed US extended nuclear deterrence commitments to both Japan and South Korea. They stressed the importance of maintaining peace and stability across the Taiwan Strait and explicitly opposed any unilateral attempt to change the regional status quo.

The statement supported freedom of navigation, overflight and lawful commerce in the Indo-Pacific in accordance with international law. The three countries also announced cooperation with the UN Office on Drugs and Crime (UNODC) to disrupt organised criminal networks — particularly scam centres in Southeast Asia accused of large-scale financial fraud using trafficked workers. Consultations on international disaster relief and maritime security cooperation were also launched.

With the agreement in place, the next test will be whether the new economic security consultation mechanism and the SMR deployment roadmap translate into concrete deliverables before the next scheduled trilateral review.