The anti-submarine drills are aimed at showing strength against North Korea.
Seoul: US and South Korean warships on Monday kicked off a round of anti-submarine drills aimed at showing strength against Stalinist North Korea.
Ten ships and 1,700 troops from both nations were taking part in the five-day manoeuvres off South Korea`s west coast, the South Korean Joint Chiefs of Staff said.
The United States Forces Korea said the war exercise, while defensive in nature, was to "enhance inter-operability and designed to send a clear message of deterrence to North Korea".
State-run media in North Korea on Sunday said the drills were a "military provocation" aimed at "mounting a pre-emptive attack" on the Stalinist state.
North Korea usually criticises joint US-South Korean military exercises as preparations for an attack.
The exercise was originally scheduled for early September but was postponed because of a typhoon and now has begun a day before the biggest meeting of the North`s ruling Workers Party in 30 years.
Observers said they believe 68-year-old dictator Kim Jong-Il plans to formally install his youngest son, Kim Jong-Un, in an important party position in preparation for his eventual succession.
The military drills are the second in a series of manoeuvres planned by the US and South Korea and smaller in scale than a previous exercise conducted in the Sea of Japan in July.
Ties between the two Koreas soured after the sinking of a South Korean corvette in March, which killed 46 sailors and which Seoul and Washington blamed on North Korea. Pyongyang denied any responsibility for the incident.