North Korea Advances Nuclear Submarine Development, Criticizes Seoul

North Korea has made notable strides in the construction of its inaugural nuclear-powered submarine, which has the potential to escalate tensions in the region.

State media reported that Kim Jong Un visited a major shipyard to assess the development of an 8,700-ton nuclear-propelled submarine, deemed essential for enhancing its naval force. Images shared by the Korean Central News Agency reveal a nearly finished hull, offering the most detailed view of the submarine so far.

The submarine is expected to be equipped with nuclear capabilities and has been identified as a “strategic guided missile submarine,” highlighting its role in reinforcing North Korea’s nuclear deterrence strategy. During the visit, Kim lambasted South Korea for its own nuclear submarine ambitions, labeling them an “offensive act” that jeopardizes North Korea's safety and maritime rights.

Kim contended that South Korea’s program only amplifies the urgency for Pyongyang to expedite its own naval nuclear capabilities. He stated that completing this submarine signifies an “epoch-making” advancement in countering perceived hostile threats.

Although the specific date of Kim’s visit was not revealed, experts suggest that the images indicate significant progress in construction. Submarine specialist Moon Keun-sik from Hanyang University pointed out that submarines are usually built from the interior out, implying that key components such as engines and possibly the reactor may already be in place.

“The visibility of the complete hull suggests the submarine could be close to being ready for launch,” Moon commented, noting that sea trials could commence within a few months if construction proceeds as currently planned.

A nuclear-powered submarine has been one of Kim's primary military objectives. It was prominently featured in a 2021 defense strategy that also encompassed solid-fuel intercontinental ballistic missiles, hypersonic weapons, reconnaissance satellites, and multi-warhead missiles. Since then, North Korea has made incremental progress in a range of these areas and recently revealed a new naval destroyer, which Kim claimed would broaden the operational reach of the country’s nuclear arsenal.

Analysts express skepticism regarding how North Korea has managed to navigate technical and financial challenges amid stringent sanctions. Some suggest that the regime's growing partnership with Russia, particularly in military matters related to Ukraine, may have provided some technical input. Others contend that the reactor is likely domestically designed, though potentially with indirect foreign assistance.

At the same time, South Korea is propelling its nuclear ambitions forward. President Lee Jae Myung has recently sought U.S. support for its own nuclear submarine project during discussions with Washington, an initiative that has received backing from U.S. President Donald Trump. However, uncertainties persist regarding the construction site and securing the sensitive reactor and fuel technology.

In another context, North Korean media indicated that Kim supervised tests on new anti-aircraft missiles, which were subsequently detected by the South Korean military. These tests emerge amidst increasingly strained relations between the two Koreas, as Pyongyang remains resistant to resuming stalled denuclearization negotiations.

As both countries pursue nuclear-powered submarines, experts caution that the strategic dynamics in Northeast Asia may be entering a precarious phase.