US, South Korea to expand nuclear submarine cooperation amid regional tensions

The US and East Asian ally, South Korea have agreed to strengthen cooperation on the nuclear-powered submarine programme which Seoul seeks to pursue amid the tensions in the Korean Peninsula.

The announcement comes as the US Secretary of Defense for Policy Elbridge Colby is on his first overseas trip in Seoul, meeting South Korean Defence Minister Ahn Gyu-back.

The cooperation also signals US push for South Korea, expecting it to take a more leading role in deterring North Korea, as reported by Reuters. 

On Saturday, Pentagon in its 2026 National Defense Strategy, called for a more limited role in deterring North Korea and urging allies to take the “burden-sharing” responsibility.

In a statement, both countries hailed the cooperation on a nuclear-powered submarine as a significant step that would strengthen South Korea’s ability to defend the peninsula and boost security alliance in the Indo-Pacific.

"Minister Cho, in particular, recalled that nuclear-powered submarine cooperation will contribute to the alliance (with the US) by strengthening South Korea's deterrence capabilities, calling for the need for concrete implementation steps through working-level talks," the statement reads.

Taking to X, Colby posted, “South Korea is a model ally that has committed to meet the global standard of spending 3.5 percent of GDP on defense and take greater responsibility for its own defense in the context of our alliance, in line with the National Defense Strategy.”

Being a key ally of the United States, South Korea hosts about 28,500 US troops. Last year, Seoul pledged to raise its defense spending to 3.5 percent of GDP.

In November 2025, South Korea and the US signed a trade agreement, including $150 billion Korean investment in the US shipbuilding sector.

Under the agreement, South Korea will build nuclear-powered submarines as part of a new partnership.

Besides nuclear cooperation, South Korea also announced plans to build two new nuclear reactors by 2038 in the midst of growing demand for clean energy.