North Korea has unveiled its first nuclear-powered submarine, a development long rumored but now confirmed by official state media. The massive size of the vessel suggests it is designed to carry long-range, nuclear-armed ballistic missiles, a significant escalation in the region’s arms race. As Pyongyang advances its nuclear deterrent, South Korea faces growing pressure to respond in kind.
This revelation has already reshaped discussions about nuclear policy in South Korea. The debate over whether Seoul should acquire its own nuclear weapons and nuclear-powered submarines has gained momentum, both in public discourse and likely within government circles.
Despite past diplomatic efforts to curb its nuclear program, North Korea has continued to expand its arsenal. In 2019, there was brief optimism for disarmament when North Korean leader Kim Jong Un met then-U.S. President Donald Trump. However, those talks ultimately led nowhere, and Pyongyang now possesses more nuclear weapons than ever.
North Korea has already demonstrated multiple methods of nuclear delivery, including land-based missiles, primitive missile submarines, and even underwater drone technology. The addition of a nuclear-powered ballistic missile submarine (SSBN) represents a major leap forward, allowing North Korea to deploy nuclear weapons far from its shores and potentially evade detection.
North Korea’s journey toward a credible sea-based nuclear deterrent began with the Gorae-class submarine, launched in September 2016. At the time, it was the world’s smallest ballistic missile submarine, capable of launching just a single missile from its sail. However, it proved North Korea’s ability to launch submarine-launched ballistic missiles (SLBMs), a crucial step in Pyongyang’s strategic ambitions.
Subsequent efforts focused on modifying older Soviet-era Romeo-class submarines to carry short-range ballistic and cruise missiles. Yet, these older designs lacked the range and survivability needed for a true second-strike capability. The newly revealed nuclear-powered submarine is the culmination of these efforts—a vessel capable of carrying larger and more advanced ballistic missiles.
Images released by North Korean state media suggest the new submarine is approximately 12 meters (40 feet) in diameter, similar to SSBNs operated by major world powers. Its length is estimated to be between 100 and 130 meters (328–427 feet), making it by far the largest submarine North Korea has ever built.
The increased size is likely necessary to accommodate advanced SLBMs, possibly from the Pukguksong family. The most recent variant, provisionally labeled Pukguksong-6, is believed to be around 13 meters (43 feet) long, comparable to U.S. Trident missiles. If reports are accurate, these missiles may have the range to strike American cities from waters near the Korean Peninsula.
Unlike North Korea’s previous submarines, which relied on conventional diesel-electric propulsion, a nuclear reactor would be required to power such a large vessel. This marks a technological turning point, as nuclear propulsion allows for much longer underwater endurance and global reach. However, questions remain about North Korea’s ability to build a reliable nuclear reactor for submarine use.
There is speculation that Russia may have played a role in assisting North Korea with submarine nuclear propulsion technology. While there is no direct evidence, North Korea has been a supplier of munitions to Russia in recent years, particularly during the ongoing invasion of Ukraine. In return, Moscow may have provided technical expertise in submarine construction, nuclear reactors, and quieting technology.
If true, this would represent a dangerous new phase in global security dynamics, as North Korea’s strategic reach extends beyond its borders. However, despite possible Russian assistance, the submarine is expected to have limited stealth capabilities and outdated sensors, meaning it would struggle against modern anti-submarine warfare (ASW) forces. Its primary mission will likely be deterrence rather than covert operations.
North Korea’s new submarine has reignited South Korea’s internal debate on nuclear armament. While Seoul remains under the U.S. nuclear umbrella, calls for an independent nuclear deterrent have been growing.
The KSS-III submarine, South Korea’s most advanced conventional submarine, already carries submarine-launched cruise missiles (SLCMs). However, a North Korean SSBN could shift the strategic balance, prompting South Korea to seek nuclear capabilities of its own.
Acquiring nuclear weapons – South Korea has the technological and industrial capacity to develop nuclear warheads in a short timeframe. While the U.S. currently discourages this, public and political support for an independent nuclear deterrent is growing.
Building nuclear-powered submarines – Unlike nuclear weapons, developing a nuclear-powered submarine is less politically sensitive. South Korea has previously explored nuclear propulsion for its submarines, though the idea has faced resistance from Washington. However, with North Korea fielding an SSBN, the strategic necessity may override past hesitations.
North Korea’s nuclear submarine is not just a regional issue—it affects the global balance of power. If South Korea moves toward nuclear weapons, it could set off a domino effect, pushing other U.S. allies like Japan and even Taiwan to consider similar options.
Additionally, North Korea’s ability to operate a nuclear-armed submarine increases the risk of miscalculation or crisis escalation. Unlike land-based missiles, which are easier to track and monitor, a submerged SSBN adds uncertainty to strategic calculations. The U.S., South Korea, and Japan will likely increase their ASW capabilities to counter this new threat.
North Korea’s first nuclear-powered submarine is a game-changer, solidifying its status as a nuclear power with global reach. While the vessel is likely years away from full operational capability, its mere existence is enough to accelerate an arms race on the Korean Peninsula.
