Defense Secretary Robert Gates predicted within five years North Korea will have a limited ability to deliver a weapon to U.S. shores using intercontinental ballistic missiles.
The risk of war on the Korean Peninsula is also rising because South Koreans are fed up with provocation and harassment from the North, Gates added to reporters in China, where he is currently visiting.
"We consider this a situation of real concern and we think there is some urgency to proceeding down the track of negotiations and engagement," he said.
U.S. officials have said North Korea's increasingly bellicose behavior over the past year is probably part of a plan to establish the military bona fides of leader Kim Jong Il's son as his chosen successor. North Korea regularly denounces the United States and accuses it of wanting to destroy the country, but it poses the most direct threat to its neighbor South Korea, a U.S. ally.
Gates said he wants to see North Korea take specific steps, such as a moratorium on nuclear and missile tests, to show that it is serious about disarmament talks. Gates said he wants to make sure North Korea is not rewarded for brinksmanship. He said the North has a pattern of bargaining by provoking a crisis, "and then everybody scrambles diplomatically to try and put Humpty Dumpty back together again. I don't want to buy the same horse twice."