April 3, 2013: South Korean Marines pass by K-55 self-propelled howitzers during an exercise against possible attacks by North Korea near the border village of Panmunjom in Paju, South Korea.AP
An unnamed spokesman for the North Korean army is warning the U.S. that its military has been cleared to wage an attack using "smaller, lighter and diversified nuclear" weapons in the latest of the country's escalating warnings.
North Korea has railed for weeks against joint U.S. and South Korean military exercises taking place in South Korea and has expressed anger over tightened sanctions for a February nuclear test.
The spokesman said in a statement carried by the Korean Central News Agency that troops have been authorized to counter U.S. aggression with "powerful practical military counteractions."
National Security Council spokesperson Caitlin Hayden called the threats "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," she said. "North Korea should stop its provocative threats and instead concentrate on abiding by its international obligations."
The Pentagon said Wednesday it was deploying a missile defense shield to Guam to protect the U.S. and its allies in the region in response to the increasingly hostile rhetoric.
The land-based missile defense system includes a truck-mounted launcher, tracking radar, interceptor missiles, and an integrated fire control system. The Pentagon said the system will boost defenses for American citizens in Guam, a U.S. territory, and U.S. forces stationed there.
On Wednesday, North Korea barred South Korean workers from entering a jointly run factory park just over the heavily armed border in the North.
The Kaesong industrial park started producing goods in 2004 and has been an unusual point of cooperation in an otherwise hostile relationship between the Koreas, whose three-year war ended in 1953 with an armistice. Its continued operation even through past episodes of high tension has reassured foreign multinationals that another Korean War is unlikely and their investments in prosperous dynamic South Korea are safe.
It is unclear how long North Korea will prevent South Koreans from entering the industrial park, which is located in the North Korean border city of Kaesong and provides jobs for more than 50,000 North Koreans. The last major disruption at the park amid tensions over U.S.-South Korean military drills in 2009 lasted just three days.
North Korea has already begun construction at a shuttered plutonium reactor that it is vowing to restart and it could be back in operation sooner than expected, a U.S. research institute said Wednesday.
The U.S.-Korea Institute at Johns Hopkins School of Advanced International Studies has analyzed recent commercial satellite imagery of the Nyongbyon nuclear facility, where the reactor was shut down in 2007 under the terms of a disarmament agreement. A cooling tower for the reactor was destroyed in 2008.
The analysis published on the institute's website "38 North" says that rebuilding the tower would take six months, but a March 27 photo shows building work may have started for an alternative cooling system that could take just weeks.
"Pyongyang may be poised to prove wrong conventional wisdom that it will take months to restart its reactor, and in the bargain it is also showing us that they mean business by accelerating the process of producing more material for nuclear weapons," said Joel Wit, 38 North editor and a former U.S. State Department official.
North Korea also said it would restart a uranium enrichment plant. Both facilities could produce fuel for nuclear weapons.
The new construction at the reactor began in the six weeks between February 7 and March 27, when another aerial image showed no building going on, 38 North says.
The analysis says the construction could be aimed at connecting the reactor to a pumping station that serves an adjacent light-water reactor that is still under construction. The light-water reactor still appears more than a year away from becoming operational but its pumping station appears from aerial imagery to be complete, it says.
But restarting the plutonium reactor would also depend on the availability of fresh fuel rods. According to 38 North, North Korea is believed to have a supply of rods, but many of them may need adapting for use in the reactor.
The North's plutonium reactor began operations in 1986 but was shut down as part of international nuclear disarmament talks in 2007 that have since stalled. Once it is up and running, the reactor is capable of producing six kilograms of plutonium a year -- enough for one or two bombs, the analysis says.
The North has already conducted three underground nuclear tests. Plans to restart the reactor and ramp up production of atomic material underscore worries about its progress in developing a nuclear-tipped missile that could target the United States. It is still believed to be years away from achieving that.
The Associated Press contributed to this report.
