We are in a race between cooperation and catastrophe, and the threat is outrunning our response.

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.

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.

Seventeen years after the Cold War, how can it be in the Unites States' national security interest for the President of Russia to have only a few minutes to decide whether to fire his nuclear weapons or lose them in response to what could be a false warning?

Senator Biden was correct by calling for more to look into Governor Cuomo's defense policy. It is clear to me, by researching the governor's record on the issue, that he would be a wildcard on national defense issues.

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.

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.