Seoul intel: Russia sends nuclear submarine reactor to North Korea

South Korean military intelligence indicates that Russia has transferred a nuclear reactor intended for use in submarines to North Korea, although the information is still being verified, according to Korean media.

Government officials believe that in the first half of 2025, Russia likely delivered two or three submarine modules to North Korea. These modules reportedly include a reactor, turbine, and cooling system — the essential components of a nuclear power plant — suggesting that Pyongyang may now possess a complete submarine reactor. The modules are believed to have been taken from decommissioned Russian submarines rather than newly manufactured.

“Since last year, North Korea has been persistently seeking nuclear submarine technology and modern fighter jets from Russia. Initially, Russia resisted, but it appears to have agreed to provide them this year,” a government source said.

For North Korea, constructing nuclear-powered submarines is a top national priority. Possessing strategic nuclear submarines capable of striking the United States is seen as the final step in completing its nuclear forces. On March 8, North Korea’s state newspaper Rodong Sinmun published photos of leader Kim Jong-un inspecting what appears to be a strategic nuclear-powered submarine under construction.

Experts note that North Korea lacks the technical capacity to quickly build a nuclear submarine, particularly since the reactor is the most critical component. Until now, the country has not been able to produce small reactors suitable for submarine use. Acquiring Russian modules could give Pyongyang access to reactor technology it has never developed independently.

Reports also suggest that North Korea has pressured Moscow to provide such technology in exchange for sending North Korean troops to support Russia’s military operations in Ukraine.

If confirmed, the transfer would constitute a serious breach of the Nuclear Non-Proliferation Treaty (NPT) and would almost certainly trigger additional international sanctions against both North Korea and Russia.

South Korea has shared the intelligence with the United States and allied countries.

By Tamilla Hasanova