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The brief skirmish ended with no casualties on the South's side, but the poorly marked maritime border has been a constant source of armed conflict, and another clash could lead to a catastrophe.
A North Korean navy ship crossed the U.N.-set sea border off the west coast and intruded into the South's territorial waters, ignoring the South Korean navy's repeated warning signals, according to Seoul's Joint Chiefs of Staff.
As the boat continued sailing southward, the South's navy fired warning shots to drive the ship away. In response, the North's ship opened fire, "directly aiming at our ship," and sparking a two-minute exchange of gunfire that left the North's boat badly damaged, the JSC said.
"This is a regrettable incident in which the North directly aimed at the South. We protest sternly," JSC spokesman Lee Ki-shik told a press briefing.
"But there were no casualties on our side," he said. The North Korean boat was half destroyed and sailed back to the North wrapped in dark smoke, helped by its towing vessel. A military source said at least one North Korean sailor was killed and three injured.
The naval clash was followed by exchanges of verbal attacks to blame each other and demand apology.
Seoul's JCS accused the North of violating the sea border, which caused the skirmish. "The North's patrol boats intruded into the South's waters 22 times so far this year," Lee said. All of them retreated before the South's warning shots, he said.
"But today, the North's warship did not return despite warning shots," he said, hinting the intrusion was a carefully calculated scheme to raise tensions.
President Lee Myung-bak convened an emergency meeting of security-related ministers and told the military to maintain high alert to counter any possible further provocative acts by the North. "The president instructed the military to react decisively, yet calmly, to make sure the situation does not further deteriorate," the presidential office said in a statement.
For its part, the North's military demanded an apology from the South, calling the skirmish a "grave armed provocation" that targeted the North’s patrol boat "on routine duty." In a statement, the Supreme Command of the North's People's Army also said that it was "always combat ready."
The clash came less than a month after the North navy warned of naval skirmishes with the South, accusing it of sending warships across their sea border.
"The reckless military provocations by warships of the South Korean navy have created such a serious situation that a naval clash may break out between the two sides in these waters," the North's navy command said on Oct. 15, adding "warnings are bound to be followed by actions."
The poorly marked western sea border, known as the Northern Limit Line, has long been a source of armed conflict between the two Koreas as the North does not recognize the borderline imposed by the United Nations at the end of the 1950-53 Korean War. The North insists on its own maritime border far south of the NLL.
The territorial sovereignty contest triggered an armed clash in 1999 and again in 2002 when the two Koreas traded naval gunfire, leaving dozens of casualties on both sides. Tensions have risen sharply in the waters during May-June and October-November crab seasons, when North Korea's fishing boats often move south in search of crab beds.
Kim Yong-hyun, a North Korea expert at Dongguk University in Seoul, said the North could take further provocative actions to retaliate for Tuesday’s clash that left the North’s boat badly damaged. "Tension along the NLL is expected to run high for the time being," he said.
Kim said the North is most likely to use the naval clash to remind the United States that the Korean peninsula is technically in a state of war, as the 1950-53 armed conflict ended without a peace treaty, in a bid to back its call for a peace treaty with Washington.
U.S. President Barack Obama is scheduled to travel to Seoul on Nov. 18-19, mainly to discuss North Korea's nuclear and military threats with President Lee.
The summit would be followed by direct contacts between the United States and the North on the nuclear issue, a standoff that Pyongyang says could be resolved with the conclusion of a peace treaty between Washington and Pyongyang.
"The skirmish seems to be timed with upcoming President Obama's Seoul visit and face-to-face talks with the United States," Kim said.
The naval clash has also reminded many of the perils of living next to the communist neighbor that invaded the South a half century ago. In September, the North suddenly released a massive flow of water from a newly constructed dam just north of the border, creating a flash flood that killed six South Korean campers.
