US Intelligence chief, James Clapper said North Korea restarted a plutonium reactor to provide a stockpile for nuclear weapons.
Pyongyang said that its main nuclear facility at Yongbyon had resumed operations last September.
“We assess that North Korea has followed through on its announcement by expanding its Yongbyon enrichment facility and restarting the plutonium production reactor,” Mr Clapper told the Senate Armed Services Committee.
He further added “We further assess that North Korea has been operating the reactor long enough so that it could begin to recover plutonium from the reactor’s spent fuel within a matter of weeks to months.”
It is estimated that about 4kg of plutonium is needed for a bomb to explode with a force of 20 kilotons.
Although Pyongyang pledged many times to stop the operations at Yongbyon, and detructed the cooling tower in 2008, however in March 2013 following a row with the U.S and U.N sanctions over third nuclear test, it vowed to restart all facilities at Yongbyon.