U.S. Secretary of State Hillary Clinton says North Korea has up to six nuclear weapons. She made the remarks in a speech on nuclear nonproliferation at the University of Louisville in Kentucky on Friday.

"The countries that we know that have actively pursued nuclear weapons that are still doing so today -- North Korea, which we know has somewhere between one and six nuclear weapons, and Iran," she said. "And that's why we're emphasizing so much international efforts against both of them to try to denuclearize the Korean Peninsula and prevent Iran from getting nuclear weapons in the first place."

Clinton did not say that the U.S. recognizes North Korea as a nuclear-armed state. Her remarks come after the U.S., in its Nuclear Posture Review issued recently, excluded the North and Iran from new limits on the use of U.S. atomic weapons. Until recently, senior U.S. officials had avoided public speculation about how many nuclear weapons the North has.

The U.S. State Department said the North should help denuclearization by returning to the six-party nuclear talks if it worries about the NPR.