CABRERA: We want to take you to the heart of the battle against ISIS in Syria. U.S.-backed rebels are getting closer to retaking the city of Raqqa. That's ISIS's self-proclaimed capitol. CNN senior international correspondent, Nick Paton Walsh, got rare access to the front line there and has this exclusive report.</s>NICK PATON WALSH, CNN SENIOR INTERNATIONAL CORRESPONDENT: We are now inside the old city walls of Raqqa, the capital of ISIS's self- declared caliphate in the territory from which they will make their final stand in Syria and really the Middle East. That wall, a key milestone for coalition forces and the Syrian Kurds and Arabs who now control fully 200 or 300 meters inside of the old city. Down that way, 200 meters, are ISIS's positions. The forces here don't move around much in the daylight because of the risk of ISIS snipers. Less so in these streets. But it's at night where the majority of the movement forward is made. We've seen U.S. forces here, not far from these positions. Anxious not to be filmed or even noticed, frankly. But you understand it's them calling in the air strikes and the artillery that's allowing these forces to move forth, frankly, so quickly. I've been surprised how little of the city ISIS are, apparently, in right now, an area possibly one and a half to three miles in terms of size. So increasingly small terrain that they hold. But as we saw in Mosul in Iraq, civilians, apparently, held in their midst, unable to flee because of the ISIS snipers. A real impediment for these Syrian Kurdish and Arab fighters. But still the progress here marking, potentially, the last time that ISIS can say they hold the city in Syria.</s>CABRERA: Incredible images. Nick Paton Walsh, thank you. We'll be right back.
On the Front Lines in Fight Against ISIS in Raqqa.