The exercises, which will run through Friday, involve troops, tanks, fighter jets and anti-aircraft guns — as well as six naval ships and Lynx anti-submarine helicopters — as the military remains on high alert for Pyongyang to retaliate for drills that Seoul held earlier this week.

North Korea had vowed to strike with lethal force if the South fired artillery shells off remote Yeonpyeong Island, the target of Pyongyang’s Nov. 23 artillery bombardment that killed four people…

Still, South Korean officials say the military will remain extra vigilant until a visible drop in provocations by Kim Jong Il’s secretive regime.

They said any retaliation from Pyongyang would likely be surprise attacks, adding that the drills demonstrate that the South is prepared for various scenarios.