The concern is they either have on hand -- or could quickly re-create the capability to produce -- vast amounts of anthrax, tons of material, compared with the several grams of material that literally shut down the U.S. postal system last year,

I think obviously it will be an issue, and my guess is that both sides will express continued concern, desire for diplomatic progress and call on Iran to be constructive.

The fear is that this sends the message that if you buck the system and stick it out long enough, you can join the club. There are a lot of nervous people when it comes to this agreement because it crosses what had been a forbidden line.

This is something that could kill thousands upon thousands of people, depending on the means of distribution.

Brazil is beginning to be perceived as a country apparently wanting to reevaluate its commitment to nonproliferation, and this is a big part of the problem.

The question is how much freedom will India have in the future to expand its weapons stockpile. This is realistically where the tension comes from.

People in the U.S. who think of and worry about Russia's nuclear weapons are a fraction of what they were during the Cold War, ... That interest or anxiety is simply not something that drives U.S. policy any more.

If the five or six bombs' worth of plutonium they are sitting on ends up going into nuclear weapons, then I think we are really reaching a watershed moment where the U.S., its troops in the region and its allies are threatened by a nuclear North Korea, with, I think, very significant regional and global consequences.

If Iran does become nuclear we do know for a fact that they have ties to terrorist organizations and we have a leadership there that has made it clear that they want to change the status quo in the region, including Israel's existence. And that's something that nobody's going to be comfortable with.