The expert, speaking on condition of anonymity, said Pyongyang may have the capacity to produce 40 kilograms of highly enriched uranium a year. In 2009, a U.S. scientist, Siegfried Hecker, was shown an enrichment plant with that capacity.
In three years, the North Koreans would have been able to produce enough material for as many as six bombs, the expert said. He estimated the nuclear program has cost the North $6.58 billion.
"If the estimated money used by North Korea to build and operate nuclear facilities converts into the price of Chinese corn, it could buy 19.4 million tons of corn," the expert said, enough to feed the population of the famine-plagued country for eight years.
A North Korean long-range rocket launch April 13 failed spectacularly. Many observers believe the country, which already faces stiffer sanctions for the rocket launch, is on the verge of another nuclear test.