North Korea threatens to ban border traffic

SEOUL, South Korea (AP) - North Korea threatened Wednesday to block all cross-border traffic and blow up any South Korean loudspeakers blasting propaganda northward after a six-year hiatus, as tensions soared over the sinking of a South Korean warship.

The dramatic deterioration in relations came as U.S. Secretary of State Hillary Rodham Clinton arrived Wednesday in Seoul for talks on how to deal with North Korea. The North also declared it will cut all ties with Seoul after it blamed the North for the March 26 sinking that killed 46 South Korean sailors.

A team of international investigators concluded last week that a torpedo from a North Korean submarine tore apart the Cheonan warship off the west coast on March 26, killing 46 South Korean sailors.

South Korea began taking punitive steps Tuesday against North Korea - ranging from slashing trade, resuming propaganda warfare and barring the North's cargo ships. Those were seen as among the strongest it could implement short of military action.

The U.S. has said evidence of the North's culpability is overwhelming and has backed the South's measures, but key North Korea ally China has said it is still weighing evidence about the incident and has done little but urge calm on all sides.

The North, which flatly denies its role in the sinking, has warned that retaliatory measures would lead to war. On Tuesday, Pyongyang announced it was cutting relations with South Korea, would expel all South Korean government officials from a joint factory park at the North Korean border city of Kaesong and start "all-out counterattacks" against the South's psychological warfare operations.

On Wednesday, the North's military issued a statement warning it would "totally ban" the passage of South Korean personnel and vehicles to an inter-Korean zone in the western coastal area, apparently referring to Kaesong, if South Korea does not stop its psychological warfare.

The statement said it would shoot at and "blow up" any loudspeakers South Korea installs at the border. Seoul dismantled such devices six years ago amid warming ties, but said Tuesday it had resumed radio broadcasts into the North and that it would reinstall loudspeakers at the border within weeks.

"The South Korean puppet warlike forces would be well advised to act with discretion, bearing deep in mind that such measures of the Korean People's Army will not end in an empty talk," said the statement, carried by the official Korean Central News Agency.

Despite the rhetoric, North Korea still allowed South Koreans workers to cross the border to enter the Kaesong complex Wednesday, according to Seoul's Unification Ministry.

The North's statement Tuesday did not refer to about 800 South Korean company managers and workers at Kaesong. Seoul also excluded Kaesong - the last remaining major joint reconciliation project that provides badly needed hard currency for Kim Jong Il's regime - from its retaliatory measures.

South Korea accused North Korea of taking "menacing" measures and will "deal with these North Korean threats unwaveringly and sternly," Unification Ministry spokesman Chun Hae-sung said Wednesday.

South Korea's military said Wednesday there were no signs of unusual activity by North Korean troops.

Four North Korean submarines, however, have disappeared from South Korean radar since they left their eastern coastal base late last week, the mass-circulation Chosun Ilbo newspaper reported, citing an unidentified Seoul official.

The paper said South Korea's military was trying to track down the location of the submarines, but the Joint Chiefs of Staff said it could not confirm the report.

A Seoul-based monitoring agency reported Tuesday that North Korean leader Kim Jong Il ordered the country's 1.2 million-member military to get ready for combat. South Korean officials could not immediately confirm the report. North Korea often issues fiery rhetoric and regularly vows to wage war against South Korea and the United States.

South Korea wants to bring North Korea before the U.N. Security Council over the sinking, and has U.S. support.

Clinton arrived in Seoul after wrapping up two days of intense strategic and economic talks with China, which responded coolly to U.S. appeals that it support international action against North Korea over the warship sinking. She met South Korea's foreign minister and planned to meet President Lee Myung-bak.

The North and South have technically remained at war since the 1950-53 Korean War ended with an armistice rather than a peace treaty.

The U.S. and South Korea are planning two major military exercises off the Korean peninsula in a display of force intended to deter future aggression by North Korea, the White House said. The U.S. has 28,500 troops in South Korea.

Relations are at their lowest point since a decade ago, when South Korea began reaching out to the North with unconditional aid as part of reconciliation efforts. Lee has taken a harder line since taking office in 2008, and the South has suspended aid.

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Associated Press writers Sangwon Yoon and Matthew Lee in Seoul, Edith M. Lederer at the United Nations, and Robert Burns in Washington contributed to this report.