SEOUL, Feb. 2 -- A nuclear-powered U.S. submarine visited South Korea for a joint annual military drill, a South Korean military official said on Monday.

"The U.S. submarine came into a South Korean port for regular visit and annual joint military exercise. We cannot confirm details on the exercise for security reasons," the Defense Ministry official said by phone.

The 7,000-ton USS Olympia, a Los Angeles-class submarine, arrived in the southern port city of Jinhae, 410 km south of capital Seoul, on Friday, a naval officer was quoted by Yonhap News Agency as saying.

The nuclear-powered submarine with no nuclear missiles came here at the invitation of the South Korean Navy to attend a ceremony marking the establishment of South Korea's Submarine Force Command in the port city later in the day.

On Sunday, the Navy launched the submarine command, 70 years after the Navy forces were created, in a bid to enhance underwater capabilities and combat readiness against the Democratic People's Republic of Korea (DPRK).

The U.S. submarine, carrying about 120 sailors and Tomahawk attack missiles, is set to hold a joint naval drill with South Korean submarines for three days from Thursday.

The joint drill would reportedly focus on detecting submarines and vessels of enemies in waters near the Korean Peninsula.

The naval exercise came after the DPRK proposed to the United States its suspension of nuclear tests in return for the suspended annual war games between Seoul and Washington this year, a proposal flatly rejected by the two nations.

The DPRK has denounced the Seoul-Washington military exercises as a rehearsal for a northward invasion, while South Korea has said such drills are defensive in nature and annually held.