The steady progress made by North Korea on its nuclear and missile programs is deeply concerning. The US cannot solve this problem alone. However, in order to take steps that could fundamentally affect the North Korean leadership and its decision-making, we need to work even more closely with our allies in the region who feel this threat acutely. I would urge China, in particular, to intensify its leadership role in helping to solve this crisis.

The Iranians know that if they develop nuclear weapons, they will be in tremendous jeopardy from military capabilities of their neighbors and of the United States. I am not predicting what will happen in 2013, but I do think it is a crucial year. I hope we can make it clear to the Iranians that we do not object to them having peaceful use of nuclear power. But when they enrich Uranium to a 20 percent level, people think they are going for the bomb. Their uranium enrichment program is a real danger.

I don't think that within a certain amount of time we can get rid of all nuclear weapons. But I do believe that, step by step, we could get others to join us. I call it going up the mountain. We can get to the top eventually, but we have to get to base camp first. Right now, we are in the valley. So we have a long way to go, but maybe our children or our grandchildren will see the top of the mountain.

If you think you're a leader, and you look over your shoulder and there ain't nobody following you, man, you're just takin' a walk.

Some people think we will see a nuclear explosion in Europe or the United States within the next 10 years. Will it happen? Sure, it's possible. But I think we can greatly diminish that risk. The only way you can do that is through cooperation, and it has to be global.

It's very hard for Europe, the US and Russia to have much influence on the growing problems elsewhere in the world unless we have our own backyard in a more stable and cooperative atmosphere.

I think if terrorists had nuclear materials and found people to put a bomb together - both of which are possible - we would already have seen a nuclear explosion. But we have literally thousands of people around the world working their tails off and making a lot of sacrifices to contain nuclear materials. I particularly would like to compliment the Russians on this. In times of great economic distress, many of them could have made an awful lot of money if they had sold their expertise.