Artillery bunkers dot a border area of North Korea's west coast, as… (Kim Jae-hwan, AFP/Getty…)
Reporting from Yichang, China and Seoul — In a pointed example of escalating tensions on the Korean Peninsula, North Korea on Monday fired more than 100 rounds of artillery into the waters off its west coast, according to South Korea's Defense Ministry.
The move came one day after the North seized a South Korean fishing boat and its seven-man crew that officials claimed had violated North Korea's exclusive economic zone.
In recent days, North Korea had vowed "strong physical retaliation" in response to South Korea's launching last week of five days of naval training exercises near the disputed sea border between North and South. The exercises ended Monday.
South Korea had also participated last month in a series of joint naval exercises with U.S. forces. Pyongyang has routinely said that it considers such operations as preparations for an invasion.
Analysts said it was still too early to link the boat seizure and the shell firings as any comprehensive North Korean response.
"That's what they said they were going to do, come back with some physical response, but if that's what they had in mind, it's too hard to tell at this point," said Daniel Pinkston, an expert in North-South relations for the think tank International Crisis Group.
He said it was important to know where the fishing boat had been taken into custody. Contrary to earlier reports, some of the artillery shells fired Monday have fallen on the southern side of the northern limit line.
The incident is expected to stir up even more tension on the peninsula. Tensions have remained high since late March, when North Korea torpedoed a South Korean military ship on patrol near the naval border, killing 46 crewmen aboard.
Although a South Korean-led investigation of the incident has pinpointed North Korea as responsible for the sinking, Pyongyang has denied any involvement.
During a briefing late Monday, the South Korean Defense Ministry confirmed that the North had fired the shells into the Yellow Sea and that authorities had evacuated fishing boats in the area, according a source who asked not to be identified.
North Korea first fired some 10 shots around 5:30 p.m., then 120 shots between 5:52 and 6:14 p.m., South Korean officials said. The South's navy raised its alert status and sent warning broadcasts to the North at 5:49 p.m. officials said.
Earlier Monday, South Korea had demanded the release of both the 41-ton fishing boat and its crew -- four South Korean and three Chinese fishermen. The crew had been briefly questioned at sea Sunday before being taken to North Korea's eastern port of Songjin, according to the South Korean coast guard.
South Korean officials said Monday that they were trying to check if the boat had entered North Korea waters. The area is also where the navies of the rival Koreas fought three bloody gun battles in recent years.
Unification Ministry spokesman Chun Hae-sung said Pyongyang had yet to provide any information on the fishermen.
"The government yesterday urged North Korea to take swift action (on the fishermen) in line with an international law and practice and I'm reiterating that," he said.
In 2009, four South Korean fishermen were detained for a month after allegedly entering North Korean waters.
Kim is a researcher in the Times' Seoul bureau