North Korea said Tuesday an agreement between South Korea and the United States to build atomic-powered submarines would cause a "nuclear domino" effect.

Last week, South Korean President Lee Jae Myung announced a security and trade agreement with Washington, including proposals to push on with developing nuclear-powered vessels.

Seoul said it had acquired "support for expanding our authority over uranium enrichment and spent-fuel reprocessing."

What is North Korea's response to the nuclear sub deal?

In its first comments responding to the deal, Pyongyang said the submarine deal was a "dangerous attempt at confrontation."

The agreement is a "serious development that destabilizes the military security situation in the Asia-Pacific region beyond the Korean peninsula and causes the situation of impossible nuclear control in the global sphere," said state-run Korean Central News Agency (KCNA).

"The joint agreement documents, released for the first time since the US and South Korea's regime changes, are indicative that US-South Korea will remain confrontational to us ... and the US-South Korea alliance will evolve to a more dangerous state, signaling a more volatile regional security situation," the statement continued.

Seoul's possession of nuclear submarines "is bound to cause a 'nuclear domino phenomenon' in the region and spark a hot arms race," the government added, adding it now means "the DPRK (North Korea) will take more justified and realistic countermeasures."

North Korean state media said last month that it had launched what it called the ninth and final test of a ballistic engine, indicating that intercontinental ballistic missile (ICBM) tests could be coming soon.

South Korea's olive branch

Tuesday's reaction from North Korea comes a day after Seoul proposed military talks with Pyongyang to prevent border clashes, the first offer of its nature in seven years.

Since becoming president in June this year, Lee has also offered to hold broader discussions with the North without preconditions, a sharp reversal from the hawkish stance taken by his predecessor, Yoon Suk Yeol, who was impeached in April 2025 after a failed attempt to declare martial law in December 2024.

Edited by: Elizabeth Schumacher