In a move that has set off alarm bells across the Korean Peninsula and beyond, North Korea has publicly unveiled images of what it claims is its first nuclear-powered submarine. The announcement, made on December 25, 2025, comes amid rising tensions following a new security and trade pact between South Korea and the United States that includes plans for the development of nuclear-powered submarines by Seoul. North Korean leader Kim Jong Un has not minced his words, labeling South Korea’s submarine ambitions a direct risk to his nation’s security and vowing countermeasures.
The images, released by North Korean state media and widely circulated by international outlets including Der Spiegel and Yonhap, depict Kim Jong Un inspecting the submarine inside a production hall. While the vessel is not yet operational, its mere existence is a bold statement. According to KCNA, North Korea’s state-run news agency, the submarine weighs a hefty 8,700 tons and is designed to launch surface-to-air missiles. The photos show Kim flanked by military officials, examining the submarine’s hull and various components, underscoring the regime’s intent to modernize its naval forces.
“The plan by South Korea and the USA to develop nuclear-powered submarines is a threat that must be countered,” Kim declared during his visit to the shipyard, as reported by KCNA. This statement, echoed by Reuters and other major news agencies, reflects Pyongyang’s deep unease over what it perceives as a growing military encirclement by its southern neighbor and the United States.
The context for this escalation is clear. In late October 2025, the United States and South Korea inked a new security and trade agreement. As part of the deal, South Korea received the green light to begin constructing its own nuclear-powered submarines, moving away from its existing fleet of diesel-powered vessels. Former U.S. President Donald Trump, in a post on his social media platform Truth Social, stated, “I have given them (referring to the South Korean government) permission to build a nuclear-powered submarine instead of the old-fashioned diesel-powered submarines they currently have.” The announcement was met with outrage in Pyongyang, which has long viewed such developments as existential threats.
North Korea’s response has been multifaceted. Besides unveiling its own nuclear-powered submarine, Kim Jong Un has reportedly set in motion a broader strategic overhaul of the country’s naval forces. During his December 24 visit, he outlined a “strategic plan to restructure the naval forces and establish new units,” according to KCNA. Details remain scarce, but the move signals a significant shift in North Korea’s military posture, with a clear emphasis on expanding underwater capabilities.
Adding to the show of force, Kim oversaw a test launch of long-range surface-to-air missiles near the country’s east coast on the same day. North Korean state media reported that the test involved a new type of high-altitude missile, successfully destroying aerial targets at a distance of 200 kilometers. This demonstration, timed to coincide with the submarine reveal, was almost certainly intended to send a message to both Washington and Seoul.
For decades, the world’s nuclear-powered submarine club has been an exclusive one. Only the United States, Russia, China, France, the United Kingdom, and India have successfully developed and deployed such vessels. These submarines are prized for their ability to remain submerged for extended periods—unlike diesel-powered subs, they don’t need to surface regularly to refuel. They’re also generally faster and quieter, making them formidable assets in any navy’s arsenal.
North Korea’s quest for a nuclear-powered submarine is not new. As Der Spiegel notes, Kim Jong Un has been vocal about his ambitions since at least 2021, when he referenced the goal during a major party congress. However, the country’s claims about new weapons systems are notoriously difficult to verify. North Korea remains one of the most isolated nations on earth, and independent access for foreign journalists is tightly controlled. “There is no real press freedom in North Korea,” Der Spiegel observes, and the regime’s pronouncements are often as much about psychological warfare as military reality.
Still, the timing and substance of Pyongyang’s latest move leave little doubt about its intentions. The submarine images and missile tests were released almost immediately after the South Korea-U.S. agreement was finalized, suggesting a direct response. Kim’s rhetoric has also grown sharper, with warnings that the new developments from Seoul and Washington represent a “threat to national security” that cannot go unanswered. As Reuters reported, Kim stated unequivocally on December 24, “South Korea’s construction of a nuclear-powered submarine poses a risk to national security.”
Beyond the immediate headlines, the episode highlights the broader arms race simmering in Northeast Asia. North Korea has conducted nuclear tests since 2006 and is believed to possess dozens of nuclear warheads, despite a raft of international sanctions. The regime has consistently justified its nuclear arsenal as a necessary deterrent against what it calls “military threats from the USA and its allied states.” Each new development—whether it’s a missile test, a submarine launch, or a diplomatic agreement—feeds into a cycle of action and reaction that has kept the region on edge for years.
For South Korea and the United States, the drive to bolster undersea capabilities is about keeping pace with regional threats. North Korea’s advances in missile and nuclear technology have forced Seoul and Washington to rethink their military strategies. The development of nuclear-powered submarines is seen as a way to enhance deterrence, improve survivability, and project power in the increasingly contested waters off the Korean Peninsula.
Yet, for many observers, the risks are clear. Each new escalation increases the chances of misunderstanding or miscalculation, with potentially catastrophic consequences. The secrecy surrounding North Korea’s weapons programs makes verification difficult, and the lack of direct communication channels means that tensions can spiral quickly. As history has shown, even small provocations in this region can have outsized effects on global security and the world economy.
Despite the bluster and brinkmanship, some analysts caution against taking every North Korean claim at face value. The country has a history of exaggerating its military achievements for propaganda purposes. Still, the images of Kim Jong Un inspecting a massive submarine—real or not—are a reminder of how quickly the security landscape can shift.
As 2025 draws to a close, the Korean Peninsula stands at a new crossroads. With both North and South Korea racing to expand their underwater arsenals, the stakes have rarely been higher. The world will be watching closely to see whether this latest round of military one-upmanship leads to dialogue—or to an even more dangerous standoff.