IAEA Director General Rafael Grossi said on Monday that South Korea's planned nuclear-powered submarine program should not raise proliferation concerns, provided a solid and specific safeguards arrangement is concluded with the International Atomic Energy Agency (IAEA). Grossi made the remarks at a press conference in Vienna, as Seoul pushes ahead with its ambition to field conventionally armed, nuclear-propelled submarines.

Where Talks Stand

Grossi confirmed that Seoul and the IAEA have already begun preliminary discussions on a safeguards framework, though the process remains at an early stage. He attributed the slow pace to the absence of specific technical details from South Korea's side regarding the envisioned submarine design, fuel type, and onshore infrastructure.

'So we are in the face of the kickoff ... of that process, which is a highly technical process where our safeguards experts meet with Korean experts, and they start looking at what will be necessary,' Grossi said.

The Core Technical Challenge

The central safeguards hurdle, according to Grossi, is ensuring accountability for nuclear material once it is loaded into submarines that can operate underwater for extended periods, outside the reach of routine inspections.

'So we need to find technical ways to ensure that the amount of uranium that left the harbour is the same when it comes back,' he said, adding that the process 'is going to take a long time precisely to ensure that there is no proliferation.'

Under the Nuclear Non-Proliferation Treaty (NPT), member states must notify the IAEA and conclude a special arrangement before operating nuclear-propelled vessels. Grossi stressed that any such arrangement must be highly specific, covering submarine design, fuel specifications, and shore-based infrastructure.

Program Details and Timeline

Defence Minister Ahn Gyu-back last month released a road map confirming that the submarines will use low-enriched uranium enriched to less than 20 per cent — well below the more-than-90 per cent enrichment level used in nuclear weapons. Seoul plans to launch its first nuclear-powered submarine in the mid-2030s and bring it into operational service before 2040.

US Backing and Bilateral Momentum

The program gained significant momentum following a summit between South Korean President Lee Jae Myung and US President Donald Trump in October. A joint fact sheet released after the summit confirmed Washington's commitment to supporting Seoul's nuclear-propelled submarine construction, as well as uranium enrichment and spent nuclear fuel reprocessing for civilian use. After some delays, the two nations launched implementation talks last week.

What Comes Next

Grossi underscored that South Korea has not yet finalised decisions on technology or operational modalities, meaning the IAEA safeguards framework cannot be fully drafted until those details are locked in. The process is expected to be lengthy, given the unprecedented nature of a non-nuclear-weapon state operating nuclear-propelled submarines under full NPT obligations. How Seoul and the IAEA resolve the underwater inspection gap will set a precedent that other aspiring submarine powers are likely to watch closely.