fired more artillery near its disputed western seaborder with on Thursday, a day after it lobbed dozens of shells during military exercisesthat prompted the South to respond with warning shots.
fired several artillery shells early Thursday thatare believed to have landed in its waters, an official at 's Joint Chiefs of Staff said. Theofficial, speaking on condition of anonymity citing department policy, said didnot respond but was closely watching the North's maneuvers.
The poorly marked sea border — drawn by theAmerican-led UN Command at the end of the Korean War — is a constant source oftension between the two .Their navies fought a skirmish in November that left one North Korean sailordead and three others wounded, and engaged in bloodier battles in the area in1999 and 2002.
It was the first exchange of fire between thetwo since November's skirmish, and could be aimed at raising tensions to emphasizethat the peninsula remains a war zone and push for a treaty formally ending the1950-53 Korean War.
and the have insisted that return to nuclear disarmament talks before any treaty can be concluded.
The North previously had announced twono-sail zones in the area, including some South Korean-held waters, throughMarch 29.
On Wednesday morning, fired about 30 artillery rounds intothe sea from its western coast and quickly responded with 100 warning shots from a nearby marine base, 's Defense Ministryand Joint Chiefs of Staff said.
The North fired more shells later Wednesdayand issued a statement saying it was part of an annual drill and that it wouldcontinue. No casualties or damage were reported.
In Washington, State Department spokesmanP.J. Crowley criticized the North on Wednesday for raising tension, saying theno-sail zone designation and the firing were "provocative actions and, assuch, are not helpful."
Pentagon press secretary Geoff Morrell alsourged the North to rejoin the six-nation nuclear talks to achieve security andinternational respect.
"Provocative actions such as those thatwe saw yesterday are clearly not part of that path," he said.
argues that it was compelled to develop nuclearweapons to cope with a military threat from the
The US and North Korea have never had diplomaticrelations because the Korean War ended in a truce, not a peace treaty, leavingthe peninsula technically at war. ,the United Nations Command and signed the cease-fire, but never did.
is said to believe a peace treaty with the would provide security and status, helpensure the survival of its government and give it a stronger hand against rival.A treaty could also raise the question of whether the needs tomaintain about 28,500 troops in the South — a legacy of the war.
"It's again confirmed that the NorthKorean regime is a warlike group that easily disrupts peace with an armedprovocation though it often talks about a peace treaty," South Korea'smass-circulation Dong-a Ilbo newspaper said in an editorial Thursday. It said should bolster its defenses against North Korean aggression.
President Barack Obama, in his State of theUnion address Wednesday night, mentioned as an example of USdiplomatic efforts to clamp down on states pursuing nuclear weapons.
"That is why now faces increasedisolation and stronger sanctions — sanctions that are being vigorouslyenforced," he said.
Separately, announced Thursday it is holding an American whocrossed into its territory from ,the second detention of a citizen it has reported in the past several weeks.
The man was detained Monday and is underinvestigation, the North's official Korean Central News Agency said. It did notidentify him by name or provide further details.
said late last month that it was holding another citizen forillegally entering the country. The man is widely believed to be Robert Park,an American missionary who reportedly crossed over a frozen river into toraise the issue of human rights.