North and South Korea have fought a brief skirmish in disputed waters, with apparent damage to a North Korean naval vessel. Pyongyang is demanding an apology, while South Korea warns the North not to engage in any more provocative behavior.
South Korea's president convened an emergency security meeting and put the navy on highest alert Tuesday after an exchange of fire with North Korea in waters west of the peninsula.
Lee Gi-sik, a senior officer with the South Korean Joint Chiefs of Staff, says a North Korean vessel crossed into the South's waters several times around midday.
He says a South Korean patrol boat fired warning shots, and then was fired on directly by the North Korean vessel. He says South Korea returned fire and drove the ship back to the North.
Lee says there were no South Korean casualties from the skirmish, which lasted only a matter of minutes. South Korean military officials say the North's boat was seriously damaged.
Illegal Chinese fishing boats were in the area, indicating North Korea may have been chasing them out of its waters.
Lee describes the clash as a regrettable incident initiated by the North. He says Seoul has lodged a strong protest with Pyongyang, demanding this type of incident never happen again.
The waters west of the Korean peninsula are one of the most dangerous potential flashpoints between North and South Korea, which remain technically at war. North Korea has never recognized a United Nations-mandated maritime border there known as the Northern Limit Line. North and South Korea fought two deadly naval clashes in the area in 1999 and 2002.
North Korean official media carried demands from the government Tuesday that South Korea apologize for what Pyongyang describes as a "grave armed provocation."
The clash comes a few days before President Barack Obama arrives in Asia, and about a week before he stops here in Seoul. The timing has drawn speculation about whether North Korea is trying to send a political message by acting provocatively.
Yang Moo-jin, a scholar with the University of North Korean Studies here in Seoul, cautions against making too much of Tuesday's incident.
He says he believes the clash was probably accidental, and took place because of what he calls the inflexibility of North Korea's military.
Still, says Yang, it serves as a reminder that tensions can escalate between North and South Korea at any moment.