North Korea stirred up fresh unease in Northeast Asia early Thursday, threatening attacks by a "smaller, lighter and diversified" nuclear force and warning, "The moment of explosion is approaching fast."
The new threat came after the North Koreans locked South Korean workers out of a joint factory complex and announced plans to restart a nuclear reactor it shut down five years ago. Meanwhile, the United States announced it was sending ballistic missile defenses to Guam, a Pacific territory that's home to U.S. naval and air bases.
"The moment of explosion is approaching fast. No one can say a war will break out in Korea or not and whether it will break out today or tomorrow," North Korea's state news agency KCNA declared in its latest broadside. "The responsibility for this grave situation entirely rests with the U.S. administration and military warmongers keen to encroach upon the DPRK's sovereignty and bring down its dignified social system with brigandish logic."
DPRK is short for Democratic People's Republic of Korea, the official name for North Korea.
Most observers say the North is still years away from having the technology to deliver a nuclear warhead on a missile. U.S. officials have said they see no unusual military movements across the Demilitarized Zone that splits the Korean Peninsula, despite weeks of bombastic rhetoric from Pyongyang, and many analysts say the increasingly belligerent talk is aimed at cementing the authority of the country's young leader, Kim Jong Un.
But the North does have plenty of conventional military firepower, including medium-range ballistic missiles that can carry high explosives for hundreds of miles. And U.S. Defense Secretary Chuck Hagel said Wednesday that the North Korean threats to Guam, Hawaii and the U.S. mainland have to be taken seriously.
"It only takes being wrong once, and I don't want to be the secretary of defense who was wrong once," Hagel told an audience at Washington's National Defense University.
But Hagel also said there was still a "responsible" path for the North to take.
"I hope the North will ratchet this very dangerous rhetoric down," Hagel said. "There is a pathway that is responsible for the North to get on a path to peace working with their neighbors. There are many, many benefits to their people that could come. But they have got to be a responsible member of the world community, and you don't achieve that responsibility and peace and prosperity by making nuclear threats and taking very provocative actions."
Shows of force and flights of bombast
The United States has in turn made a show of its military strength in the annual drills, flying B-2 stealth bombers capable of carrying conventional or nuclear weapons, Cold War-era B-52s and F-22 Raptor stealth fighters over South Korea.
KCNA blamed the U.S. and its South Korean allies for the situation, however.
"We formally inform the White House and Pentagon that the ever-escalating U.S. hostile policy toward the DPRK and its reckless nuclear threat will be smashed by the strong will of all the united service personnel and people and cutting-edge smaller, lighter and diversified nuclear strike means of the DPRK and that the merciless operation of its revolutionary armed forces in this regard has been finally examined and ratified," it said. "The U.S. had better ponder over the prevailing grave situation."
Caitlin Hayden, National Security Council spokeswoman, slammed North Korea's statement as "unhelpful and unconstructive."
"It is yet another offering in a long line of provocative statements that only serve to further isolate North Korea from the rest of the international community and undermine its goal of economic development. North Korea should stop its provocative threats and instead concentrate on abiding by its international obligations," she said.
Robert Carlin, a North Korea expert at the Center for International Security and Cooperation at Stanford University in California, told CNN that the rhetoric is still "too hot. It needs to be cooled down." But he added, "If we say that we don't see any actions yet from them, I have to assume that the U.S. military still thinks the situation is under control."
North Korea's Wednesday decision to prevent South Korean workers and managers from entering the Kaesong Industrial Complex, which sits on the North's side of the border but houses operations of scores of South Korean companies, is a tangible sign of the tensions between the two sides.
North Korea has demanded the withdrawal of South Korean workers by April 10 from the complex, South Korean semi-official news agency Yonhap said Thursday. But South Korea's ministry of unification denied the report.
It's a move that could end up hurting Pyongyang financially, since Kaesong is considered to be an important source of hard currency for Kim's government. More than 50,000 North Koreans work in the zone, producing hundreds of millions of dollars worth of goods each year.
Those workers earn on average $134 a month, of which North Korean authorities take about 45% in various taxes.
The North had threatened over the weekend to shut down the industrial complex. North Korea has yet to grant permission for South Koreans to enter the complex, South Korea's ministry of unification said Thursday. The nearly 800 South Koreans remaining inside the complex are still able to leave, the ministry said.
A 'cash cow'
"We are highly skeptical that they will close this cash cow, as some recent reports have suggested," Stephan Haggard, professor at the School of International Relations and Pacific Studies at the University of California, San Diego, wrote in an article published Monday.
"But if they did, the costs would be higher for the North than for the South," Haggard wrote in the article for the Peterson Institute for International Economics, a Washington-based research organization.
Seoul said it "deeply regrets" the North's decision to stop South Koreans from entering Kaesong.