You're forgetting that one of the reasons why ISIS exists in the first place was the chaos the U.S. invasion created in Iraq
Which occurred because the US wasn't willing to be sufficiently brutal in clamping down on it.
How do you know?
(The most obvious example of US willingness to be sufficiently brutal seems like Vietnam, which wasn't a responding success.)
Here's my op-ed that uses long-term orientation, probabilistic thinking, numeracy, consider the alternative, reaching our actual goals, avoiding intuitive emotional reactions and attention bias, and other rationality techniques to suggest more rational responses to the Paris attacks and the ISIS threat. It's published in the Sunday edition of The Plain Dealer, a major newspaper (16th in the US). This is part of my broader project, Intentional Insights, of conveying rational thinking, including about politics, to a broad audience to raise the sanity waterline.