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IAEA chief says Seoul's nuclear submarine project would require 'ironclad guarantees'

Published: 15 Apr. 2026, 18:34 Updated: 15 Apr. 2026, 20:00

SEO JI-EUN
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International Atomic Energy Agency (IAEA) Director-General Rafael Grossi speaks at a press conference at the Four Seasons Hotel in Jongno District, central Seoul, on April 15. [KANG JEONG-HYEON]

Rafael Grossi, director-general of the International Atomic Energy Agency (IAEA), on Wednesday signaled the start of formal discussions with Seoul over its nuclear-powered submarine ambitions, while warning that such a project would require "ironclad guarantees" to prevent it from undermining global nonproliferation standards.

Speaking at a press conference in Seoul during a visit to Korea this week, Grossi described his scheduled meeting with South Korean Foreign Minister Cho Hyun as a "kickoff" for high-level technical talks.

The visit comes as Seoul pushes ahead with plans to build nuclear-powered attack submarines following U.S. approval secured through a summit between President Lee Jae Myung and U.S. President Donald Trump last October.

"The use of nuclear technology to power submarines has a number of technical considerations which are very important," Grossi said. "Because of the very nature of the ships that goes for long periods on missions, the nuclear material is excluded from [regular] inspection and not seen by IAEA inspectors [for long periods of time.]"

Grossi emphasized that, because these submarines could carry large quantities of enriched uranium — potentially even highly enriched uranium (HEU), depending on the design — South Korea must enter into "special arrangements" with the agency. These would include advanced technical monitoring to ensure nuclear material is not diverted for weapons use while the vessels are at sea.

South Korea, a non-nuclear-weapon state and a signatory to the Treaty on the Non-Proliferation of Nuclear Weapons, currently operates under a Comprehensive Safeguards Agreement with the IAEA covering its civilian nuclear facilities. The framework does not extend to military vessels; however, a separate agreement is required specifically for submarine fuel. Broader Korea-U.S. consultations on the submarine program have been delayed since January.

An official from the Foreign Ministry told the Korea JoongAng Daily that it is seeking to use close IAEA engagement to push back against concerns in some quarters of the international community that the program amounts to acquiring latent nuclear capability, with officials emphasizing the peaceful propulsion intent of the submarines throughout the process.

South Korean Foreign Minister Cho Hyun, right, and IAEA Director General Rafael Grossi hold a meeting at the Ministry of Foreign Affairs in central Seoul on April 15 to discuss South Korea's nuclear-propelled submarine project and North Korean nuclear issues. [MINISTRY OF FORIEGN AFFAIRS]

Grossi noted that South Korea’s situation differs from other nations currently pursuing similar capabilities — with Australia’s Aukus project a "complex trinational mechanism" involving the United States and Britain, while Brazil’s project is "entirely domestic," built around a self-developed pilot reactor.

For Seoul, he said, "there are still a number of question marks" around both the construction of the submarines and the source of their fuel, adding those issues were "still to be clarified."

He said he had been "reassured" by Cho's assurances that South Korea would maintain its nonproliferation commitments "to the full," calling those statements "unambiguous and very important, so as to prevent other countries from believing that we are in a sort of unbridled race toward nuclear weapons."

Regarding North Korea, Grossi said the IAEA monitors the country entirely through satellite imagery and external analysis since its inspectors were expelled in 2009.

He confirmed a "rapid increase" in operations at the Yongbyon nuclear complex, including the 5-megawatt reactor and a light water reactor.

"All of them point to a very serious increase in the capabilities of the DPRK in the area of nuclear weapons production, which is estimated at a few dozen warheads," Grossi said, referring to the acronym for North Korea's official name, the Democratic People's Republic of Korea.

Grossi declined to confirm reports that U.S.-Iran nuclear peace talks in Islamabad had centered on a ten-year enrichment moratorium rather than Iran's proposed five-year moratorium, as he was not present at the negotiations.

Technically speaking, he added, there is "no big difference between five, ten or twenty years" and that is a "matter of political confidence."

"Without verification, any agreement is just a piece of paper, or a promise," Grossi said.

Iran currently holds approximately 440 kilograms (970 pounds) of uranium enriched to 60 percent, primarily at a site in Isfahan, Grossi confirmed.

International Atomic Energy Agency (IAEA) Director-General Rafael Grossi, third in left row, speaks at a press conference at the Four Seasons Hotel in Jongno District, central Seoul, on April 15. [KANG JEONG-HYEON]

Grossi's visit to Seoul also had a dimension beyond his role at the IAEA.

He is among the leading candidates for the next UN Secretary-General, with selection process underway and Security Council vote expected soon after April debates.

"If I am elected, I could start a common endeavor to restore confidence and make the UN an institution that makes a difference for the good," he said.

He also met former UN Secretary-General Ban Ki-moon earlier that day in Seoul, calling the conversation "interesting."

In a readout of their meeting released by Seoul's Foreign Ministry, Cho expressed deep concern over the situation in the Middle East and hope for an early restoration of peace through U.S.-Iran cease-fire negotiations — including the resumption of free navigation through the Strait of Hormuz. Grossi reaffirmed that North Korea's nuclear program remains a top priority for the IAEA and expressed support for South Korea's diplomatic efforts toward peace on the peninsula.

UPDATE, April 15: Added details from the meeting with Foreign Minister Cho Hyun.

BY SEO JI-EUN [[email protected]]