The South Korean navy moves into position for a seven-day military exercise.
Two destroyers and a number of patrol ships mobilized as the drill began on Wednesday (February 6).
Authorities say the exercise aims to test the detection of ballistic missiles and close-range weapons systems.
The drill comes just days after a joint naval exercise with the U.S., in an apparent show of force against North Korea.
Tension on the Korean peninsular is running high amid fears the North could conduct a third nuclear test.
South Korea launches military drill (0:38)
Feb. 9 - The South Korean navy conducts exercises at sea as tensions over a possible nuclear test by North Korea run high. Sarah Charlton reports. ( Transcript )