Sanliurfa, Turkey — As the U.S. watched from the sidelines Tuesday, Russian President Vladimir Putin emerged as the key power player in Syria, reaching an agreement for a new six-day ceasefire with Turkish President Recep Tayyip Erdogan. The deal between Erdogan and Putin will hold off a Turkish offensive in eastern Syria for another six days. Turkey will get a 20 mile safe zone along its border.

But this is much more than a ceasefire agreement. American troops are leaving eastern ,ceding influence to Russia. The Russians have stepped into the power vacuum. They're already patrolling territory once controlled by America and its allies.

The U.S. withdrawal opened the door to a Turkish offensive, targeting Kurdish fighters that Turkey says are a terrorist group. But the Kurdish forces have been America's closest partners in the campaign against ISIS on the ground in Syria. They said they've been betrayed by the U.S. and have now stopped fighting ISIS.

Then there's the fate of the roughly 12,000 accused ISIS fighters that Kurdish forces said they're still holding. CBS News was given exclusive access to one of their prisons last month, where they showed security video of an attempted escape. It's unclear who'll now be in charge of keeping them locked up.

With American troops now leaving eastern Syria — and the Kurdish-forces sidelined — the question now is who will continue the battle against ISIS. That could be up to the Russians.