South Korea is pushing to build nuclear-powered submarines, a move Seoul says has received political backing from U.S. President Donald Trump and could help relieve pressure on an increasingly stretched U.S. submarine fleet in the Pacific. South Korean officials argue the plan would strengthen deterrence against North Korea and China, while allowing U.S. forces to focus on other regional flashpoints. President Lee Jae Myung has framed the effort as a way to improve undersea tracking near the Korean Peninsula and reduce the operational burden on U.S. naval forces. We reached out to South Korea’s Ministry of National Defense and the White House for comment.
Why It Matters
The Indo-Pacific has become the center of global undersea competition, with China, Russia, and North Korea rapidly expanding their submarine fleets. U.S. officials have warned for years that American attack submarines are being retired faster than they are replaced, straining patrol coverage across multiple regions. Allowing South Korea to operate nuclear-powered submarines could deepen alliance burden-sharing in areas such as the South China Sea and waters around Taiwan, while raising questions about nuclear nonproliferation and regional escalation.
What To Know
South Korea aims to join a small group of countries that operate nuclear-powered attack submarines, which can remain submerged for extended periods, travel faster, and operate more quietly than diesel-electric boats. The effort has long been constrained by the U.S.–South Korea nuclear cooperation agreement, which restricts Seoul from reprocessing spent nuclear fuel. That restriction moved into public view in October when Lee raised the issue directly with Trump. Trump later wrote on Truth Social that he had approved South Korea building nuclear-powered submarines, though no formal U.S. policy document has been released.
South Korean defense officials say the country already has much of the industrial capacity required. Defense Minister Ahn Kyu-back told lawmakers that South Korea has secured “various conditions” needed to build nuclear-powered submarines, while retired naval officers have pointed to the design of the Jangbogo-III submarine class as adaptable to nuclear propulsion. In 2019 testimony to Congress, then–Indo-Pacific Command chief Adm. Philip Davidson warned that roughly three-quarters of the world’s submarines operate in the Indo-Pacific. As of mid-2025, the U.S. Navy listed fewer than 50 attack submarines.
Caveat: No finalized agreement has been released detailing fuel supply, technology transfer, or construction location. Defense analysts say congressional approval and technical reviews could delay operational deployment for a decade or more.
What People Are Saying
Donald Trump, writing on Truth Social, said he had approved South Korea building nuclear-powered submarines, calling diesel-powered vessels “far less nimble.” Yu Jihoon of the Korea Institute for Defense Analyses said nuclear-powered submarines would be a “game-changer” for countering North Korea’s undersea threat. Thomas Shugart, a retired U.S. Navy captain at the Center for a New American Security, has questioned whether the capability is operationally necessary given South Korea’s proximity to potential conflict zones. North Korea’s state media and China’s Foreign Ministry have both warned the move could increase regional tensions.
What Happens Next
Any move toward construction would require U.S. congressional approval, interagency reviews involving the Departments of Defense, State, and Energy, and further negotiations on fuel handling and technology transfer. Until formal agreements are released, South Korea’s nuclear-powered submarine plans remain long-term.
This report draws on publicly available statements and prior reporting by CNN, the U.S. Navy, and South Korean defense officials.
