My apologies for not weighing in sooner on Michael Levi's extremely useful new book. I have long felt that overly pessimistic views on our ability to prevent acts of nuclear terrorism have gotten in the way of more sensible policies, not only on this issue but on broader foreign policy objectives.

Nonetheless, in the spirit of debate and discussion, I want to raise a few questions that we might discuss further this week.

My first question involves claims regarding the conservative, "risk averse" nature of major terrorist organizations. Although I have some sympathy with this logic, I don't find it fully persuasive. Do we have enough evidence to suggest that this is the case? Aren't there folks out there who would see an act of nuclear terrorism as the ultimate strike against the infidel enemy? So, I'd like to hear more on this aspect of the argument, which really goes more to motivation than to capabilities. In my view, the limited ability of a terrorist group to "succeed every time," as Michael suggests, is the strongest argument for a more realistic set of policies on nuclear terror.

What about the argument that a "terror state" like Iran might share nuclear weapons with a terrorist group? I see this as highly unlikely, for a variety of reasons: 1) Given all of the effort that would go into developing such a weapon, no government would be likely to share it; 2) the government in question could not control how a terrorist group might use such a weapon; 3) If there were any possibility of tracing the origins of a bomb to a given state, that nation would be subjected to a devastating retaliatory attack that could well end its ability to function as a modern society. Since all tyrants want to survive and wield power, this would be a substantial deterrent to sharing weapons with terrorists. However, even if these arguments make sense (along with others that Michael or other participants in this dialogue may have to offer up), we need to do a much better job of communicating this to the broader public. The recent NIE on Iran should presumably make it much harder to use this argument as a sort of "scare tactic of last resort," but that may or may not be true down the road.

Finally, what should be our priorities? My candidate for job one is to expand threat reduction programs that will secure or destroy "loose nukes" and bomb-making materials in Russia and beyond. Our ability to do this requires not only more resources, but some sort of turn for the better in U.S.-Russian relations, which are continuing to deteriorate as we speak. Scaling back or (ideally) eliminating plans to place missile defense components in Poland and the Czech Republic might be a starting point for such a rapprochement with Russia, but there would obviously need to be other elements.

So, these are my initial thoughts. Looking forward to further discussion in the next few days.