A US nuclear submarine has arrived in the South Korean port city of Busan, Yonhap news agency reported, citing the South Korean navy.
The arrival of the USS Missouri, also known as SSN-780, comes after South Korea and the US held their second nuclear advisory group meeting in Washington on December 15.
"Any nuclear attack by North Korea against the United States or its allies is unacceptable and will lead to the end of the Kim regime," a joint US-South Korean statement from the meeting said.
A senior South Korean official said earlier this week that North Korea may attempt to launch an intercontinental ballistic missile this month.
Visits by U.S. nuclear submarines were previously rare but have increased under agreements between Seoul and Washington that increased the arrival of U.S. military assets to help deter North Korea.
Another US nuclear submarine, the USS Santa Fe, docked in port on the South Korean island of Jeju in November.
The USS Carl Vinson, an American aircraft carrier, also arrived in Pusan Harbor last month. /BGNES