The U.S. denounced North Korea for its "long history of bellicose rhetoric" after the totalitarian state said it's in a state of war with neighboring South Korea and threatened to close a joint industrial zone.
"We take these threats seriously and remain in close contact with our South Korean allies," White House spokeswoman Caitlin Hayden said in an e-mailed statement Saturday. "But we would also note that North Korea has a long history of bellicose rhetoric and threats" and the latest statement "follows that familiar pattern."
North Korea Saturday threatened to shut a jointly run industrial zone in its border city of Gaeseong in response to flights over the south by U.S. stealth bombers. Tensions have risen since North Korea detonated a nuclear device in February, defying global sanctions.
"It seems there are no more cards left for North to pressure South now, and Gaeseong seems to be the last resort," Yang Moo Jin, a professor at the University of North Korean Studies in Seoul, said by phone Sunday. "Chances of them closing it are very slim, almost impossible."
About 200,000 North Koreans, including workers and their families, depend on the Gaeseong industrial zone for income, Yang said. The North generates about $100 million profit annually from the joint project and the South makes quadruple that amount, he said.
The last time tensions were at this level between the two sides was in 2010, following the sinking of a South Korean warship, Cheonan, which killed 46 sailors, and North Korea's shelling eight months later of a South Korean border island, in which four people died.
"Every issue raised between the North and South will be dealt with in a wartime manner," the state-run Korean Central News Agency said Saturday, citing what it called a special statement. U.S. stealth bomber flights over South Korea this week are "unacceptable" and North Korea's statement is a "final warning" to the U.S. and its allies, KCNA said.
Kim Jong Un's regime this month cut off a military hot line with South Korea, put artillery forces on high alert and threatened pre-emptive nuclear strikes, drawing condemnation from U.S. Secretary of Defense Chuck Hagel.
"It's part of what I call March Madness on the Korean Peninsula," said Kenneth Quinones, professor of Korean studies at Akita International University in Japan. "Every March when the U.S. and South Korea hold military maneuvers, North Korea goes on full alert and makes similar threats. The only difference is the rhetoric has intensified, and the situation certainly merits concern and close monitoring."
North Korea may "ban the south side's personnel's entry into the zone and close it," an unidentified spokesman for the General Bureau for Central Guidance to the Development of the Special Zone said Saturday in a statement carried by KCNA.
No unusual North Korean troop movements have been detected since North Korea's threat to close Gaeseong, and South Korean businesspeople spending the night there are safe, Unification Ministry spokesman Kim Hyung Suk said by phone from Seoul.
"We regret these continued threats and urge the North to retract them," said the spokesman. Emergency communication channels with South Koreans in Gaeseong are operating to ensure their security, he said.
Gaeseong is the last remaining example of inter-Korean cooperation. More than 120 South Korean companies employ about 53,000 North Koreans at the complex. From its opening in 2005 through Jan. 31, goods totaling more than $2 billion have been produced there, according to Unification Ministry data.
About 900 South Koreans regularly visit Gaeseong, located about 10 miles (16 kilometers) north of the demilitarized zone, the world's most heavily fortified border.
Almost 800 South Koreans were stranded in Gaeseong in March 2009 after North Korea temporarily severed communications. North Korea also briefly cut ties in 2010 after an international panel found it responsible for the sinking of the Cheonan.
Four North Korean websites were inaccessible Saturday due to what may be a "loosely coordinated effort by hackers," according to a website that monitors Internet activity on the Korean peninsula. North Korea's main Naenara web portal and the homepages of KCNA, the state-run airline Air Koryo, and the Voice of Korea, a broadcast outlet, were malfunctioning, North Korea Tech said on its website.
South Korea's Unification Ministry spokesman said some North Korean sites seemed to be periodically working.
South Korea's armed forces "will continue to closely monitor the North's military movements" and "comprehensively punish any instances of provocation by the North," Kim Min Seok, a Defense Ministry spokesman, said by phone.
North Korea on March 29 put some units on standby after Hagel on March 28 denounced North Korea's "provocative actions and belligerent tone." Kim met with military leaders and ordered the preparations after two U.S. B-2 stealth bombers flew over South Korea on March 28 in a show of deterrence.
That followed earlier overflights by B-52 bombers as the U.S. and South Korea held a two-month exercise named Foal Eagle, an annual event scheduled to include about 10,000 soldiers.
"The situation of the Korean peninsula being neither at peace nor at war has come to an end," KCNA said Saturday. The countries remain technically at war because their 1950-1953 conflict ended without a peace treaty.
"It is extremely regrettable that North Korea continues to make provocative statements, including this one, and to carry out provocative actions," Japanese Foreign Ministry Deputy Press Secretary Naoko Saiki said by phone. Japan will keep working with other countries, "seeking to have North Korea carry out its obligations." Two calls to China's Foreign Ministry seeking comment on the North Korean statement went unanswered outside business hours. Kim's country relies on its neighbor for diplomatic and economic support.
"Barring any incident, I expect a gradual softening," said Quinones, who worked for the U.S. State Department before joining the university in Akita. "I don't think war is inevitable. I'm optimistic cooler heads in Washington and Seoul will prevail." North Korea's rhetoric has had little impact so far on South Korean stocks, as the benchmark Kospi index gained 2.9 percent this week, its best performance in six months.
"Technically the two countries have been at war, just stopped fighting," Sebastien Galy, a foreign-exchange strategist in New York at Societe Generale SA, wrote in a note to clients received Saturday. "But in the game of rhetoric it feels a bit like closing the door behind you."