A senior South Korean marine on Thursday defended the 10 minutes it took to retaliate after a North Korean attack amid criticism the response was too slow.
Two days after North Korea fired a barrage of artillery shells at the island of Yeonpyeong, killing two civilians and two soldiers and destroying dozens of houses, members of President Lee Myung-bak's own party and opposition lawmakers accused the military of acting too late.
Marine Lieutenant-General Joo Jong-hwa told reporters visiting the island on Thursday it took 10 minutes to return fire, contradicting earlier reports that it took 15.
"The soldiers did not desert and in the midst of a rain of fire, they pinpointed the target and started firing which has never occurred in the past before," he said. "They did very well."
North Korea says it was retaliating to live fire from South Korea into its waters after warning the South by phone not to go ahead with a drill.
"North Korea argues that we fired at them first, but this is the direction that we fired," he said, pointing southwest, away from North Korea.
He said there were fewer North Korean fishing boats in the area than before. "We believe that North Korea has still not eased its firing readiness," he added.
South Korea said on Thursday it would increase troops on islands near North Korea with Pyongyang warning it would follow its bombardment with more attacks if its neighbour tried any "provocations".
Hundreds of terrified residents of Yeonpyeong fled to the mainland on Wednesday after the heaviest attack on the Korean peninsula since the end of the Korean War 1953, many saying they would never return.
Yeonpyeong, a small island just 120 km (75 miles) west of Seoul, is home to about 1,600 civilians and 1,000 soldiers. It lies in Yellow Sea waters claimed by the North but occupied by the South since the end of the war.
The United States and South Korea are to hold joint military exercises in the Yellow Sea from this weekend, with the aircraft carrier USS George Washington taking part.