Daniel L. Byman

The [Trump administration's] proposals don't call for constant monitoring once someone is in the country. It seems like [Saipov, the NYC attacker] became much more radical relatively recently. So the ideas on the table don't seem particularly relevant to this attack.

Such unthinking measures [that target Muslims] might benefit Trump politically while inadvertently helping the terrorists operationally.

This is a movement that historically has been highly divided. One thing Osama had been doing is trying to be a unifier. He was very comfortable working with people who agreed with him on one issue and disagreed with him on five. Toward the end of his life, a lot of what he was trying to do was to get groups to work together.

The image people often have is plane-loads of these [jihadists] flying out, but that’s the wrong image: It’s people filtering out in dribs and drabs.

What do you do when your allies [like Pakistan] are part of the problem? The desire to turn our backs on these people is there, but then you worry that terrorists will have more operational freedom and it will cost you more in the long run.

[The Islamic State] is a very strong group which has a lot of sympathizers, its ideas are embedded and it has networks. It has a lot to draw on even as it loses its physical territory