"We will send a message to those nuclear scientists: If you want to come clean and expose an illegal weapons program, then we will help you and we will protect you," Edwards said at North Carolina University's Wilmington campus, according to a transcript provided by his campaign.

Edwards said Republican President George W. Bush had not done enough to stop the spread of weapons of mass destruction.

"We will bring the world together to end the nuclear weapons programs in states like North Korea and Iran," he said.

"The administration has stood on the sidelines while they advanced their nuclear programs."