The White House and the State Department said they were taking seriously an almost daily string of threats from North Korea toward the US and South Korea, ratcheted up a notch when the North said it would revive its long-dormant reactor and ramp up production of nuclear weapons material.
But officials cast doubt on whether North Korea would follow through, portraying the latest threat as part of a pattern of antagonistic taunts that, so far, have not been backed up by action.
“There’s a long way to go between a stated intention and actually being able to pull it off,” said State Department spokeswoman Victoria Nuland.
Still, the US is taking steps to ensure it has the capacity to defend itself and its allies against any threats from North Korea, and President Barack Obama is being updated regularly, said the president’s spokesman, Jay Carney.
“The entire national security team is focused on it,” Mr Carney said.
North Korea said that scientists will quickly begin “readjusting and restarting” the facilities at its main Nyongbyon nuclear complex, which was shuttered as part of international nuclear disarmament talks in 2007 that have since stalled. Officials said those operations would include the plutonium reactor and a uranium enrichment plant, both of which could produce fuel for nuclear weapons.
Mr Carney called the North’s announcement a violation of its international obligations and said that while North Korea has obtained nuclear weapons in the past, it has not tempered the US resolve to see the Korean peninsula rid of nuclear weapons.
He called on Russia and China, two countries he said have influence on North Korea, to use that influence to persuade the North to change course.
North Korea’s recent tide of nuclear vows and aggressive threats are seen as efforts to force Washington into disarmament-for-aid talks and to boost young leader Kim Jong Un’s stature as a strong military leader. Pyongyang has reacted angrily to US-South Korean military drills and a new round of UN and US sanctions that followed North Korea’s February 12 underground nuclear test.
North Korea has barred South Korean workers from entering a jointly run factory park just over the heavily armed border in the North, officials in Seoul said.
The move came a day after Pyongyang announced it would restart its long-dormant plutonium reactor and increase production of nuclear weapons material.
The bid to bar South Koreans from entering the Kaesong factory park, the last remaining symbol of detente between the rivals, comes amid increasing hostility from Pyongyang. It has threatened to stage nuclear and missile strikes on Seoul and Washington and said that the armistice ending the 1950s Korean War is void.
Seoul’s unification ministry spokesman Kim Hyung-suk said Pyongyang is allowing South Koreans to return home from Kaesong, but that about 480 South Koreans who had planned to travel to the park on Wednesday were being refused entry.
He said North Korea cited recent political circumstances on the Korean Peninsula when they delivered their decision to block South Korean workers from entering Kaesong. The two sides do not allow their citizens to travel to the other country without approval, but an exception has previously been made each day for the South Koreans working at Kaesong. The Korean Peninsula is technically in a state of war because the Korean War ended in a truce not a peace treaty.
North Korea is angry about current South Korea-US military drills and new UN sanctions over its February 12 nuclear test, its third.
Dozens of South Korean firms run factories in the border town of Kaesong. Using North Korea’s cheap, efficient labour, the Kaesong complex produced 470 million US dollars (£310 million) worth of goods last year. Pyongyang threatened last week to shut down the park, which is run with mostly North Korean labour and South Korean know-how. It expressed anger over South Korean media reports that said North Korea would not shut the park because it is a source of crucial hard currency for the impoverished country.
In 2009, North Korea closed its border gate in anger over US-South Korean military drills, leaving hundreds of South Korean workers stranded in Kaesong for several days. The park later resumed normal operations.
Meanwhile US defence secretary Chuck Hagel is calling North Korea’s development of nuclear weapons a “growing threat” to the US and its allies. In a telephone call to Chinese defence minister Chang Wanquan, Mr Hagel cited North Korea’s pursuit of nuclear weapons and ballistic missiles and said Washington and Beijing should continue to co-operate on those problems.
A Pentagon statement describing the phone call also disclosed that General Martin Dempsey, chairman of the Joint Chiefs of Staff, will visit China later this month. It would be his first trip to China as head of the Joint Chiefs. Mr Hagel also invited the Chinese defence minister to visit the US this year.
South Korean soldiers walk on the empty road after vehicles were refused entry to North Korea (AP