The Bush administration is warning North Korea against reviving efforts to produce weapons-grade material for nuclear bombs.
The warning from White House Spokesman Ari Fleischer follows word from defense officials that North Korea appears to be poised to restart its nuclear bomb-making operation.
Mr. Fleischer says, if Pyongyang does, it will be what he terms "another provocative action" intended to intimidate and blackmail the international community.
He says that community is trying to seek a peaceful solution to the crisis over North Korea's nuclear program.
The Pentagon believes North Korea already has one or two nuclear weapons.
But officials now say they have detected activity that could mean North Korea is moving nuclear fuel rods, possibly to a reprocessing facility, where they could be converted to weapons-grade material.
That could enable Pyongyang to produce more nuclear arms.
But defense officials say the North might have another plan - to sell the enriched material on the international market.
In either case, they agree it could give North Korea leverage to force the United States into negotiations at a time when the Bush administration appears preoccupied with Iraq. One defense official says North Korea would be foolish not to try to take advantage of that.
These officials, speaking on condition of anonymity, say the Pentagon is monitoring developments closely.