Ask Onix
US approves South Korea's nuclear submarine program amid regional tensions
The United States has formally approved South Korea's plan to develop nuclear-powered attack submarines, marking a strategic shift in the allies' defense cooperation as tensions escalate with North Korea and China. The agreement, announced by the White House on Thursday, includes collaboration on fuel sourcing and technical requirements for the submarines, which Seoul argues are critical to countering Pyongyang's advancing nuclear capabilities.
Key details of the agreement
The deal follows a broader trade accord reached last month, where South Korea secured a reduction in U.S. tariffs from 25% to 15% after pledging $350 billion in investments-$200 billion in direct cash and $150 billion in shipbuilding projects. According to a White House fact sheet, the U.S. will "work closely to advance requirements for this project, including avenues to source fuel," signaling a deeper integration of the two nations' defense and economic ties.
Only six nations-the U.S., China, Russia, the UK, France, and India-currently operate nuclear-powered strategic submarines. South Korea's existing fleet of roughly 20 diesel-powered submarines lacks the range and stealth of nuclear vessels, which can operate submerged for months and traverse vast distances at higher speeds.
Strategic implications for the Korean Peninsula
South Korean officials frame the program as a direct response to North Korea's nuclear ambitions, which include its own recently unveiled submarine project, potentially aided by Russia. In March 2025, Pyongyang released images of leader Kim Jong Un inspecting a nuclear submarine under construction, with analysts estimating the regime could deploy such vessels within years. North Korea is also believed to possess around 50 nuclear warheads, exacerbating regional instability.
Defense Minister Ahn Gyu-back hailed the nuclear submarines as a "proud achievement" that would keep Kim Jong Un "awake at night," while experts note the move aligns with Seoul's limited options to counter Pyongyang's nuclear arsenal.
"South Korea cannot develop its own nuclear weapons to counter North Korea's," said Yang Uk of the Asan Institute for Policy Studies. "What's something they can do? Fielding nuclear submarines."
Regional reactions and geopolitical ripple effects
China, which has increasingly asserted naval dominance near South Korea's maritime borders, reacted cautiously. Chinese Ambassador to South Korea Dai Bing urged Seoul to handle the issue "prudently," citing "complex and sensitive" security dynamics. Analysts suggest Beijing is likely "furious" over the deal, which strengthens the U.S.-South Korea alliance at China's expense.
For Washington, the agreement serves dual purposes: pressuring North Korea while countering China's regional expansion. "Trump has put the burden of defense spending on South Korea," Yang Uk noted, adding that Seoul's expanded defense budget will effectively act as "America's proxy" in the broader Indo-Pacific strategy.
Logistical hurdles and next steps
Despite President Trump's claim that the submarines would be built at a Hanwha-owned shipyard in Philadelphia-ostensibly to boost U.S. jobs-South Korean officials insist domestic production is essential for timeliness. Prime Minister Kim Min-seok testified in parliament that the Philadelphia facility "does not have the capability" to construct such vessels. Hanwha has not publicly addressed the discrepancy.
The immediate priority is revising the bilateral nuclear agreement to permit U.S. fuel transfers and establish safeguards for military use. Meanwhile, South Korea's defense ministry has emphasized the submarines' role in enhancing "interoperability" with allied navies, particularly the U.S. and Japan, amid rising threats.
Expert perspectives: A symbolic or transformative move?
Opinions diverge on the submarines' strategic impact. Jo Bee-yun of the Sejong Institute called the deal a "major change," enabling South Korea to project power "fast and far" alongside regional partners. Others, like Yang Uk, caution that while the submarines bolster deterrence, they may also entrench North Korea's justification for its nuclear program, complicating future disarmament negotiations.
"This reinforces Pyongyang's narrative that nuclear weapons are necessary for survival," Yang Uk warned. "It's a double-edged sword."
