As catastrophic as a nuclear attack would be, it would be self-contained.

As catastrophic as a nuclear attack would be, it would be self-contained. But if you look at a worst-case scenario for a biological attack, it would be difficult to determine whether or not it was a terrorist attack, and it would be far more difficult to contain.

When you look at all instruments of statecraft and how that's pulled together, I think the ambassadors are uniquely poised.

However, Libya has made enormous progress in the last couple of years and we are hopeful that at some point we can address that question.

But despite this shared perception of the threat, there is disagreement over the most effective means to counter the threat. Some European countries continue to argue that terrorism is merely -- or mainly -- a criminal problem.

It is now well known that the terrorist cell that conducted the 9/11 attacks did much of its planning from a base in Europe.