The move comes as the United States and South Korea are in the midst of two months of joint military drills, which started on March 1, and on Monday they began another planned joint exercise that involved bringing 2,500 troops from the United States. Stirring up a sense of crisis among its impoverished people, North Korea was also staging an unusually vigorous military drill.
However, there were no signs of hostility along the border. South Korean officials said they were increasing their vigilance amid fears that North Korea might use the United States-South Korean drills and a fresh round of United Nations sanctions as an excuse to create an armed skirmish.
“We must deal strongly with a North Korean provocation,” the South’s new president, Park Geun-hye, said during her first cabinet meeting on Monday. She called for the protection of people living on a border island that was attacked by North Korean artillery in 2010 and of South Koreans working in a joint industrial park in the North Korean border city of Gaesong.
But she also said her two-week-old government would work to build “trust” with North Korea.
During the cabinet meeting, Ms. Park criticized senior military officers for golfing last weekend amid tensions with the North. Her office is investigating news reports that a military golf course here was crowded with senior officers, including generals.
Kim Min-seok, spokesman of the Defense Ministry, admitted that some officers played golf at the weekend. But he added that none served in sensitive commanding posts.
In Washington, the Treasury Department imposed new sanctions on North Korea’s Foreign Trade Bank and the State Department blacklisted three senior members of the North Korean government. Tom Donilon, President Obama’s national security adviser, called the steps part of an effort to “work with allies and partners to tighten national and international sanctions to impede North Korea’s nuclear and missile programs.”
The exchange of bellicose language between the Koreas has recently intensified, recalling the level of tension after the North Korean artillery barrage in 2010, which left four South Koreans dead. After the United Nations imposed the new sanctions as a penalty for the North’s third nuclear test, on Feb. 12, the North said it would nullify the armistice and might pre-emptively attack Washington and Seoul with nuclear weapons. South Korea responded that if there were such attacks the North Korean government would be “erased from the Earth.”
On Monday, the North’s official Korean Central News Agency said the armistice had been nullified. The North followed through on another threat as well, cutting off a Red Cross hot line.
However, the two continued to operate channels of communication to allow hundreds of South Koreans to commute to the Gaesong industrial complex, one of the last remaining symbols of inter-Korean cooperation.
North Korea had often threatened to nullify the armistice, especially when the United States and South Korea were conducting drills.
The United States and South Korea started two months of regular drills, called Foal Eagle, on March 1. They involve 10,000 Americans, many brought in from bases outside South Korea. The additional drills that began Monday, named Key Resolve, involve 10,000 South Koreans and 3,000 Americans, along with more sophisticated American aircraft and warships. “The aggressive Key Resolve exercise by the United States and its puppet war maniacs is a clear declaration of war against our republic," said the North’s Committee for the Peaceful Reunification of the Fatherland, the agency in charge of relations with South Korea.
In a visit Monday to a coastal artillery unit that faced Baeknyeongdo, South Korea’s northernmost island, North Korea’s leader, Kim Jong-un, called the disputed waters around the island “the most volatile tinderbox" on the Korean border and ordered the soldiers to “deliver a merciless retaliatory strike" at any enemy intrusion, North Korea’s news agency reported.