North Korea Resumes Firing Artillery Amid Tension

North Korea fired more artillery near its disputed western sea border with South Korea on Thursday, a day after it lobbed dozens of shells during military exercises that prompted the South to respond with warning shots.

North Korea fired several more artillery shells early Thursday that are believed to have landed in its waters, an official at Seoul's Joint Chiefs of Staff said. The official, speaking on condition of anonymity citing department policy, said South Korea did not respond but was closely watching the North's maneuvers.

The poorly marked sea border — drawn by the American-led U.N. Command at the end of the Korean War — is a constant source of tension between the two Koreas. Their navies fought a skirmish in November that left one North Korean sailor dead and three others wounded, and engaged in bloodier battles in the area in 1999 and 2002.

It was the first exchange of fire between the two Koreas since November's skirmish, and could be aimed at raising tensions to emphasize that the peninsula remains a war zone and push for a treaty formally ending the 1950-53 Korean War.

South Korea and the United States have insisted that North Korea return to nuclear disarmament talks before any treaty can be concluded.

The North previously had announced two no-sail zones in the area, including some South Korean-held waters, through March 29.

On Wednesday morning, North Korea fired about 30 artillery rounds into the sea from its western coast and South Korea quickly responded with 100 warning shots from a nearby marine base, Seoul's Defense Ministry and Joint Chiefs of Staff said.

The North fired more shells later Wednesday and issued a statement saying it was part of an annual drill and that it would continue. No casualties or damage were reported.

In Washington, State Department spokesman P.J. Crowley criticized the North on Wednesday for raising tension, saying the no-sail zone designation and the firing were "provocative actions and, as such, are not helpful."

Pentagon press secretary Geoff Morrell also urged the North to rejoin the six-nation nuclear talks to achieve security and international respect.

"Provocative actions such as those that we saw yesterday are clearly not part of that path," he said.

North Korea argues that it was compelled to develop nuclear weapons to cope with a military threat from the U.S.

The U.S. and North Korea have never had diplomatic relations because the Korean War ended in a truce, not a peace treaty, leaving the peninsula technically at war. North Korea, the United Nations Command and China signed the cease-fire, but South Korea never did.