SEOUL, South Korea - North Korea's powerful military announced Wednesday it will shut the country's border with the South on Dec. 1 -- a marked escalation of threats against Seoul's new conservative government at a time of heightened tension on the peninsula.
The military's chief delegate to inter-Korean talks informed his South Korean counterpart that the North will "restrict and cut off" cross-border routes next month, state-run Korean Central News Agency said.
Analysts called it a pointed political move designed to humiliate Seoul by hobbling a joint industrial park in the city of Kaesong, just across the border, that has served as a beacon of hope for reconciliation.
Relations between the two Koreas -- separated by troops, tanks and one of the world's most heavily armed borders since a three-year war that ended in a truce in 1953 -- have been frosty since South Korea's President Lee Myung-bak took office in February.
Lee pledged to be tough with communist North Korea, an abrupt departure from his liberal predecessors' decade-long policy of fostering reconciliation with aid and other concessions.
Pyongyang reacted by cutting off diplomatic ties with Seoul. Ties deteriorated further in July when a North Korean soldier fatally shot a South Korean tourist visiting Diamond Mountain, with Seoul banning tours to the jointly operated resort in the North.
After months without contact, the North's military summoned South Korea to the border for talks last month, only to berate Seoul over anti-Pyongyang leaflets that continue to flutter over the border in helium-fueled balloons.
The two Koreas had agreed in 2004 to end propaganda warfare across the border, but the South says it cannot prohibit activists from dispatching the leaflets, citing freedom of speech.
Wednesday's warning -- the North's most concrete, calculated threat yet -- amounts to an ultimatum to the Lee administration to acknowledge that it must abide by past agreements, analysts said.
"This is a critical juncture in their estimation that they have to take some action," said Paik Hak-soon of South Korea's Sejong Institute. "They feel that they have waited enough."
The warning is "very, very serious," said Lim Eul-chul of Kyungnam University's Institute for Far Eastern Studies in Seoul. "This is an escalation of North Korea warnings."
The tension comes amid questions about the health of North Korea's leader, Kim Jong Il. U.S. and South Korean officials say Kim, 66, suffered a stroke, but North Korea denies he was ever ill.
Pyongyang's tactic may be to wear Seoul down. However, the Lee administration has stood its ground and said little Wednesday about the North's latest move. "Waiting is sometimes a strategy," Lee said, according to his spokesman.
The North's decision to shut the border is "regrettable," said Kim Ho-nyeon, the Unification Ministry spokesman.
Paik said Pyongyang may use Kaesong to humiliate Seoul. Shutting down Kaesong would be a "serious blow to South Korean politics. It will start off a debate what went wrong with North Korea policy."
The Kaesong complex has been a key source of hard currency for the impoverished North and a symbol of reconciliation: South Korean firms send raw materials through the border and the goods come back stamped "Made in Kaesong."
Lim said he doubted North Korea would kick everyone out Dec. 1.
"They will take gradual steps to pressure our government to change their policy. That is their main goal."
He and other analysts noted that North Korea has a pattern of using provocation as a negotiating tactic, both with South Korea and with other nations seeking to disarm the Korean peninsula.
On Wednesday, the North's foreign ministry announced that it won't allow outside inspectors to take samples from its main nuclear complex to verify its accounting of past nuclear activities. It also complained about a delay in energy aid shipments.
The North said it never agreed to such sampling, contradicting statements by U.S. officials. The conflicting statements could prove to be a new snag in the long process of nuclear disarmament on the Korean peninsula.
North Korea has agreed to give up its nuclear weapons but had bickered with the U.S. over verification, with Washington insisting on strict measures to ensure Pyongyang is not hiding atomic programs.
The U.S. Embassy in Seoul had no immediate comment on the North's statement. South Korea called the North's statement "disappointing." In Washington, the U.S. announced that it has shipped 50,000 metric tons of fuel oil to North Korea.
