Why is Trump fighting ISIS in Syria?

ISIS is satanic, cruel and amorphous; it disseminates its ideology through the internet

The Trump foreign policy team has been all over the map on what to do next in Syria — topple the regime, intensify aid to rebels, respond to any new attacks on innocent civilians. But when pressed, there is one idea everyone on the team seems to agree on: “The defeat of ISIS,” as Secretary of State Rex Tillerson put it.

Well, let me add to their confusion by asking just one question: Why?

Why should our goal right now be to defeat the Islamic State in Syria? Of course, ISIS is detestable and needs to be eradicated. But is it really