Nick Schifrin:

The horror of Syria's war has felt endless. Half a million dead. Millions displaced.

But the battlefield has shifted dramatically. Take a look at this map. September 30th, 2015, the day Russia intervened. The Syrian government, in red, controlled pockets across the west. ISIS controlled a spider web in the center and east.

And this is today. The Syrian government, in red, has made dramatic progress. ISIS, in black, reduced to a small area. Anti-government rebels, in green, only have a few pockets. The most important is Idlib. That is the likely last, major battle of the Syrian war.

The yellow is Kurdish controlled.

And take a look at these photos from the Kurdish area. A Syrian mother named Batool with her baby, and Batool with Gayle Tzemach Lemmon, who just returned from the Kurdish-controlled areas, and joins us now. She is an adjunct senior fellow at the Council on Foreign Relations.

And also joining me is Paul Salem, president of the Middle East Institute, and the author, most recently, of "From Chaos to Cooperation: Toward Regional Order in the Middle East".

Thank you to you both.

Paul Salem, let me turn to you. Why is Idlib so important?