South Korea and the United States are deepening their alliance and setting the stage for a more self-reliant and capable South. Recent agreements on trade, defense and cooperation on nuclear-powered, conventionally armed submarines highlight how the U.S. is supporting Seoul’s long-term military and industrial capabilities.
The allies in late October 2025 reaffirmed a trade and security agreement to advance economic and security interests. Seoul pledged to invest $350 billion in the U.S., with $150 billion earmarked for shipbuilding and $200 billion for strategic technological sectors such as semiconductors, energy, artificial intelligence and quantum computing.
Washington, meanwhile, will support South Korea’s efforts to build nuclear-powered, conventionally armed submarines. The U.S. also will help its ally meet technical requirements for the submarines, “including avenues to source fuel,” the nations stated.
South Korean President Lee Jae-myung called the submarines “a decades-old dream of South Korea and a vital strategic asset for peace and stability on the Korean Peninsula,” according to the UPI news agency.
Seoul’s fleet of diesel submarines are not equipped to track and outmaneuver Chinese and North Korean vessels, Lee said. Nuclear-powered submarines traditionally can travel faster and farther than diesel vessels.
South Korea’s economy relies on exports, requiring safe and predictable transportation.
Analysts say the submarine deal is a milestone for South Korean defense resilience. Joining only a handful of nations with nuclear-powered submarines will strengthen the South’s ability to monitor maritime threats while bolstering its naval-industrial base. The agreement also boosts Seoul’s ambitions in the nuclear energy sector, including potential civilian enrichment and spent-fuel recycling.
Meanwhile, South Korea pledged to increase defense spending to 3.5% of its gross domestic product. The nation also will acquire $25 billion in U.S. military equipment by 2030.
Defense experts say Seoul’s moves are steps toward strengthened self-reliance. The longtime alliance now supports South Korea not only through extended deterrence, but also by enabling Seoul to develop and sustain its own high-end capabilities.
Washington also outlined bilateral industrial cooperation, including a shipbuilding working group on maintenance, repair and overhaul, shipyard modernization, workforce training, and supply-chain resilience.
“These initiatives will increase the number of U.S. commercial ships and combat-ready U.S. military vessels as quickly as possible,” including potential construction of U.S. vessels in South Korea, the White House stated.