North Korea said on Thursday that the deployment of US strategic assets in South Korea met the conditions for its use of nuclear weapons, state media KCNA reported.
The country also accused the United States and South Korea of escalating tensions in the region, said the report, citing a statement by the country's defense minister.
The remark appears aimed at the Ohio-class US nuclear-powered submarine which arrived at a port in the southern city of Busan earlier this week.
The report comes after a US soldier crossed the border into North Korea on Tuesday at a time of heightened tension between the two Koreas and the United States.
North Korea has yet to comment on the incident involving the US soldier.