The two Koreas traded artillery fire on Wednesday in renewed tensions between the rival neighbors just as they resumed high-level contact for the first time after more than two years.
The South Korean military said nuclear-armed North Korea twice fired shells along their tense border, drawing warning shots from the South's marines in response.
It appeared that North Korea was conducting drills off the west coast of the divided peninsula and some of their shells landed close to the maritime border, according to the South's military officials.
The exchange of fire occurred around Yeonpyeong Island, a South Korean military and civilian outpost that lies in territory the North considers its own.
Yeonpyeong had been placed on high alert with military reinforcements since North Korea launched artillery attacks on the island last November, killing four South Koreans including two civilians and damaging scores of buildings.
The South Korean government came under heavy criticism then for failing to react with force.
In the first incident Wednesday, North Korea fired three shots just around noon, and the South returned three artillery rounds toward the same area about an hour later, international news agencies reported.
At dusk, the North fired three more shots, at least one of which landed near the border, triggering return fire from the South, a Souith Korean military official said.
"It is our assessment that it [the shelling] was part of a training exercise by the North," a South Korean military official was quoted saying by Reuters news agency.
No imminent aggression
He said there was no unusual activity in the North indicating imminent aggression
But the firing in early afternoon briefly sparked alarm on Yeonpyeong, where some 1,800 civilians live along with the Marine garrison.
"The residents were preparing to evacuate their homes for shelters since they went through a similar thing in the past," a spokeswoman for Ongjin county, which oversees the island, told Agence France-Presse.
Wednesday's skirmish saw no casualties, and it was not immediately clear whether it could derail diplomatic efforts aimed at the resumption of six-nation talks over the North's nuclear weapons program.
Pyongyang had expressed interest in restarting stalled six-nation nuclear disarmament talks.
Nuclear envoys from the two Koreas held rare talks during an Association of Southeast Asian Nations (ASEAN) security forum in Indonesia last month, and a senior North Korean official visited New York later for discussions with U.S. officials.
The two Koreas are still technically at war, having only signed a truce to end the 1950-53 Korean War.
Press reports last month indicated North Korea was gearing up for a large military exercise appeared to be aimed at countering annual joint U.S.-South Korean war games next week.
In March last year, a South Korean warship was torpedoed in an attack that killed 46 sailors. The South blamed the attack on Pyongyang, but the North denied it was responsible.
In another sign of tensions, South Korean media reported this week that a team of North Korean agents have been assigned to kill South Korea's defence minister after he vowed Seoul would retaliate militarily if Pyongyang repeats attacks against the South. Reported by RFA's Korean service. Written in English by Parameswaran Ponnudurai.