The longer Russia prolongs its war in Ukraine, the more the global balance of power shifts. Recently, Moscow reportedly supplied North Korea with nuclear submarine modules, including a reactor, a move that could mark a breakthrough for Pyongyang in building its own strategic submarines, Korea JoongAng Daily reports, citing South Korean government sources.

According to several officials, during the first half of 2025, Russia may have delivered two or three modules to North Korea, including a reactor, turbine, and cooling system, which are the key components of a nuclear submarine’s power plant. These were not newly produced units but parts removed from decommissioned Russian submarines.

“Since last year, North Korea has been persistently requesting nuclear submarine technology and advanced fighter jets from Russia.

Russia was initially reluctant but appears to have agreed to provide them this year,” one government source said on condition of anonymity.

A shadow beneath the Pacific

For Pyongyang, nuclear-powered submarines are a strategic priority, as they could enable the capability to launch nuclear strikes against the US. In March, the state-run Rodong Sinmun published photos of Kim Jong Un inspecting a nuclear submarine under construction.

Until recently, experts were convinced that North Korea could not independently develop a reactor for submarines. If the transfer of modules is confirmed, the country would gain access for the first time to a technology that had been out of reach.

Reports also suggest Pyongyang demanded this assistance from Moscow in exchange for sending troops to support Russia’s war in Ukraine.

A red line crossed

Confirmation of the transfer would mean Russia has crossed a “red line,” in blatant violation of the Nuclear Non-Proliferation Treaty (NPT). Such a step would likely provoke new sanctions targeting both North Korea and Russia.

South Korea’s intelligence service has already passed the information to the US and its allies.