South Korea launches biggest-ever military drill

South Korea launched its largest-ever anti-submarine exercise on Thursday, despite the North's threats of retaliation. The five-day drill, which includes live-fire training, is taking place near South Korea's disputed Yellow Sea border with North Korea.

Reuters

South Korea is mobilising 4,500 troops, 29 ships and 50 aircraft.

The South says it will not tolerate provocations during the drill, which is being staged in response to what it says was a deadly North Korean torpedo attack on a warship.

Pyongyang denies responsibility for the sinking of the Cheonan in March.

The latest exercise comes eight days after South Korea and the United States ended a massive joint naval and air drill in the Sea of Japan.

South Korea's joint chiefs of staff said the latest exercise is "defensive" in nature.

Marines stationed on islands near the Yellow Sea border with the North will stage live-fire battery exercises, but the guns will be trained south-west.

The North's military has condemned this week's exercise as a "direct military invasion", and warned "reckless naval firing" by the South would be countered "with strong physical retaliation".