The United States and South Korea have unveiled the details of a sweeping new trade and security agreement that paves the way for Seoul to build nuclear-powered submarines for the first time — a move set to significantly reshape regional military dynamics and fuel geopolitical debate across Northeast Asia.
The announcement came as South Korean President Lee Jae Myung confirmed that Washington had granted official approval for South Korea to develop nuclear-powered attack submarines under a major partnership spanning shipbuilding, artificial intelligence, and nuclear technology.
The deal includes $150bn in South Korean investment in the US shipbuilding sector, alongside an additional $200bn in broader US industrial investments, according to a fact sheet released by the White House.
Yonhap news agency reported that, in return, Washington agreed to lower trade tariffs on Korean imports from 25 percent to 15 percent, resolving one of the most contentious issues in bilateral economic talks.
A Landmark Expansion of Military Cooperation
At a press conference in Seoul, President Lee hailed the agreement as a turning point:
“One of the greatest variables for our economy and security has been finalised,” Lee said.
“The United States has given approval for the Republic of Korea to build nuclear-powered attack submarines.”
Lee also noted that South Korea secured expanded authority over uranium enrichment and spent nuclear fuel reprocessing, areas traditionally restricted under global nonproliferation norms.
According to Yonhap, Seoul aims to acquire at least four 5,000-ton, conventionally armed nuclear-powered submarines by the mid-2030s, marking South Korea’s entry into a small and elite group of nations with such advanced maritime capabilities.
Military analysts say this step will significantly upgrade Seoul’s naval reach, improve its deterrence posture, and raise its profile as a defense technology leader.
Conflicting Signals on Where Submarines Will Be Built
US President Donald Trump previously claimed on social media that South Korea’s first nuclear submarine would be built in Philadelphia Shipyards.
But Seoul quickly contradicted that assertion.
National Security Adviser Wi Sung-lac clarified on Friday:
“From start to finish, the leaders’ discussion proceeded on the premise that construction would take place in South Korea.”
He added that the question of location is now “settled,” underscoring Seoul’s intention to build and maintain full domestic capability.
China Warns of Rising Tensions
Beijing reacted sharply even before the agreement was formally announced.
China’s ambassador to Seoul, Dai Bing, warned that such cooperation:
“Goes beyond a purely commercial partnership, directly touching on the global nonproliferation regime and the stability of the Korean Peninsula and the wider region.”
China has long opposed any expanded nuclear-related cooperation between Washington and its allies, arguing it threatens regional balance and could provoke further militarization.
North Korea Expected to Respond
Pyongyang has not yet commented, but military analysts expect a response soon.
North Korea routinely accuses the United States and South Korea of building up military forces near its borders in preparation for a possible invasion. In September, it unveiled its first nuclear attack submarine, though analysts have questioned its true operational capabilities.
The new US–ROK pact is likely to intensify North Korea’s rhetoric and accelerate its own weapons development cycle.
Broader Strategic Implications
The agreement’s fact sheet emphasizes the creation of a shipbuilding working group to expand both US commercial fleets and “combat-ready US military vessels.”
The move comes amid rising military rivalries in the Indo-Pacific:
- China’s rapid naval expansion
- North Korea’s advancing missile and submarine programs
- Strengthening trilateral cooperation between the US, South Korea, and Japan
- Australia’s own investment in underwater “Ghost Shark” drones under AUKUS
Together, these developments point to a region rapidly adapting to new maritime competition.
A Transformational Deal With Global Consequences
South Korea’s push for nuclear-powered submarines marks one of the most significant shifts in its defence posture in decades and reflects growing concern about threats in the region.
For Washington, it tightens strategic cooperation with a key ally at a moment of heightened geopolitical friction.
For Beijing and Pyongyang, it represents a worrying sign of deeper US military influence right on their doorstep.
And for the wider region, it introduces a new era of undersea competition whose consequences will unfold over the next decade
