SEOUL — South Korea launched its first nuclear-powered submarine in a live-fire missile drill on Wednesday.
Sources: Yonhap, Reuters, AP, BBC, The Guardian, The Korea Herald, The Diplomat, Nikkei Asia, Arms Control Today, RFA
SEOUL — South Korea launched its first-ever nuclear-powered submarine in a live-fire ballistic missile drill on Wednesday, a watershed moment in Northeast Asian security that immediately drew condemnation from North Korea and a diplomatic protest from China.
The RSSNK Gunja — South Korea’s first 3,000-ton nuclear-powered submarine, commissioned in April with US assistance — test-fired a Hyunmoo-B ballistic missile while submerged in the Sea of Japan. The drill, observed by US Indo-Pacific Command officials, lasted 90 minutes and was described as a demonstration of extended deterrence in action.
President Lee Jae-myung watched from the underground command bunker in Pyeongtaek, calling it a new chapter in South Korea’s defence posture. The US State Department said the drill was a sovereign decision and fully consistent with alliance commitments.
North Korea’s state news agency called the drill an unforgivable nuclear provocation and warned it would respond with overwhelming nuclear force if the submarine was deployed to the East Sea. China’s foreign ministry said it had serious concerns and called on all parties to exercise restraint. Japan said it was monitoring the situation closely.
The submarine represents a major leap in South Korea’s undersea capabilities — nuclear power gives it near-unlimited range and the ability to remain submerged for months, unlike the country’s existing diesel-electric fleet. That changed in February 2026 when President Trump approved the transfer of US nuclear propulsion technology to South Korea under the revised Guidelines for Nuclear Weapon Employment.
South Korea’s defence ministry said the submarine’s reactor was based on the same low-enriched uranium design approved by the IAEA and that no weapons-grade material would ever be on board. Arms control groups expressed concern that operationalising a nuclear submarine fleet would complicate the non-proliferation landscape in Northeast Asia.
North Korea has conducted four nuclear tests and possesses an estimated 40 to 50 nuclear warheads. South Korea’s defence budget for 2026 is $47.5 billion, the largest in the country’s history. The drill came 72 hours after North Korea test-fired two Hwasong-19 intercontinental ballistic missiles in a simulated nuclear strike on Seoul.
Regional analysts said the submarine deployment would accelerate a regional arms race in submarine capabilities, with Japan and China likely to accelerate their own programs. Australia said it welcomed a stronger Indo-Pacific undersea deterrent. South Korea’s stock market fell 1.8 percent on the news before recovering, while the won weakened 0.4 percent against the dollar.
Sources: Yonhap, Reuters, AP, BBC, The Guardian, The Korea Herald, The Diplomat, Nikkei Asia, Arms Control Today, RFA
Written by Kenji Tanaka, Asia-Pacific Bureau Chief