Exactly one month after North Korea bombarded Yeonpyeong island, South Korea's military has staged a brief but large show of force. The country's president told troops his patience with Pyongyang has run out.
South Korean army troops fire shells from howitzers and tanks. Overhead, attack helicopters and jets drop bombs in an exercise to repel a mock North Korean invasion at a training ground 30 kilometers from the heavily fortified border.
President Lee Myung-bak Thursday addressed an army unit in the mountains near the Demilitarized Zone dividing the Korean peninsula. The president says South Korea will not strike first but if North Korea attacks it will be hit with a strong blow.
Lee said he had hoped patience with Pyongyang would bring peace to the Korean peninsula but that has turned out to be a mistake.
Pyongyang's official news agency quotes North Korea's armed forces minister saying the military, armed with its nuclear deterrent, is ready for a "sacred war." The North accuses South Korea of preparing to launch a war with its recent military exercises.
Thursday's drill was part of South Korea's response to North Korea's shelling of Yeonpyeong island on November 23. Two South Korean marines and two civilians died attack.
The bombardment of the island came hours after South Korea's military fired artillery into disputed coastal waters as part of a pre-announced drill.
The South Koreans also are conducting a three-day anti-submarine exercise off the east coast, where the maritime boundary is not contested. That drill ends Friday.
Tensions began to escalate on the peninsula when a South Korean war ship exploded and sank in the Yellow Sea in late March, killing 46 of the crew. An international investigation blamed a North Korean torpedo attack. Pyongyang denies responsibility.
The two Koreas have no diplomatic relations and technically have remained at war since a 1953 truce halted fighting in their civil war.