The top U.S. counterterror official says ISIS presents a threat to U.S. security but is not as grave a threat as Al Qaeda. National Counterterrorism Center Director Matthew Olsen says at a Brookings Institute event that the group could inspire a lone wolf attack by a sympathizer in the U.S.:
[ISIS] poses a direct and significant threat to us [and] has the potential to use its safe haven to plan and coordinate attacks in Europe and the United States
But it is not as capable of carrying out a large-scale attack as al Qaeda was before 9/11:
ISIL is not al Qaeda pre 9/11. We are not what we were pre 9/11. We are so much better postured, in so many ways, to see, detect, stop any attack like what we saw on 9/11.
The major threat is to U.S. troops in Iraq:
We have no credible information that ISIL is planning to attack the United States … in the near term, we’re focused on protecting our personnel on the ground in Iraq.