It doesn’t take a rocket scientist.
Speaking strictly on “military might” ISIS is rated slightly less dangerous than the Chilean Coast Guard. If America wanted them gone, it would take an hour.
“If America wanted them gone, it would take an hour.”
What is missing is the will to do what needs to be done.
There are only two ways to defeat an insurgency: you either win over the local populace to your side, or you kill the local populace along with the insurgents. We don’t have much luck doing the first, and we don’t have the nerve to do the second.