AUDIE CORNISH, HOST:

The U.S.-brokered cease-fire in northern Syria has ended. So far, there are no reports of major fighting. A reason for that is a separate agreement announced by the Russian and Turkish presidents today. Now, that deal recognizes Turkey's security zone in northern Syria. Not only that, it also says Russian troops will help Turkey enforce it.

For more, we're joined by NPR's Peter Kenyon in Istanbul and Jane Arraf in Dohuk, near Iraq's border with Syria. And we're going to start with Jane.

Jane, what are you hearing about the situation in northern Syria in this moment? Is it still relatively peaceful?

JANE ARRAF, BYLINE: Well, depends how you define peaceful. Earlier, one of the key Kurdish Syrian factions had said fighting actually was continuing between Kurdish forces and Turkish mercenaries. But a U.S. administration official says General Mazloum Kobani, who's a key Kurdish Syrian commander, had sent a letter to Vice President Pence saying they'd fully withdrawn. But that U.S. official also pointed out that the U.S. is unable to monitor the cease-fire. It does not know what's going on there. It doesn't have surveillance over the area, so it's all a bit murky but safe to say no major fighting. And in any case, that cease-fire seems to have been extended.

CORNISH: And, Peter, speaking to us from Istanbul, it seems like the U.S.-brokered cease-fire is now being replaced by a Russian-Turkish one. So what do you know about how that's going to work?

PETER KENYON, BYLINE: Well, it reads like an agreement designed to push the YPG Kurdish fighters back away from the area Turkey wants to call a safe zone along the border. It also seems intended to prevent further bloodshed. So starting on Wednesday, Russian forces and Syrian border guards will be moving into the area outside Turkish control and pushing YPG forces further back. YPG fighters also agreed to leave Manbij, an area further west on the border, but not Qamishli to the east, near the Iraqi border.

And there will also be joint Turkish-Russian patrols under this agreement. They're setting out a six-day period for all these things to be accomplished and up and running. Of course, how YPG forces react to all this and its implementation will be pretty critical.

CORNISH: Jane, speaking of that, where are the U.S. troops who used to work with the Kurds to secure that Syrian-Turkish border area?

ARRAF: Well, as of today, some of them are actually in Iraq. They crossed the border from Syria yesterday - huge convoy rolling across that border and through the Kurdistan region of Iraq, where a lot of Kurds were really dismayed, disappointed and felt betrayed because the Kurds here are also really strong U.S. allies.

So the plan had been for them to continue through to western Iraq to a base there. But the Iraqi government said today that they actually didn't have permission to stay in Iraq. So the U.S. defense secretary is scrambling and saying he's discussing that with the Iraqi defense minister. And basically, President Trump has called for some to stay in Syria - a few of them to stay to protect oil fields from ISIS and some expected to stay at a small base near the Syrian border.

CORNISH: Is there any reaction from them - from the Kurds to the Russian-Turkish agreement?

ARRAF: There's no official reaction yet, but there is likely to be dismay at an agreement that actually forces them out of a larger area than that agreement that was brokered by the U.S. We reached some people in Rojava, which is what the northeastern Kurdish region is known as in Syria. And one of them said they can live with any agreement, basically, as long as the Turks don't take over. They said they can live with the Syrians. They can live with the Russians but not the Turks.

But if you look at what's happening on the ground, it includes 7,000 Syrian Kurds so far who have fled across the border. They're terrified. And that's with the closed border. So the level of fear there is quite intense, as well, as to what might happen with this.

CORNISH: Peter, there's a constellation of alliances here, and I'm hoping you can give us a sense of the bigger picture. How does this affect U.S. interests in Syria, U.S. relations with Turkey?

KENYON: Well, I mean, the U.S. has left the field in Syria, of course. They have abandoned their former partners against ISIS, the YPG Kurdish fighters. And with the U.S. absent, the Turks have begun working in turn with the Russians, who bring their own strengths and their own agendas.

The dynamics, of course, change pretty dramatically. Whereas the U.S. was a backer of the rebels - these Kurdish fighters - Russia is the main ally of the Assad regime in Damascus. And basically, if the U.S. thinks Turkey is going to be pressing American interests in Syria under these circumstances, it's a bit hard to see how that would work. So I guess the bottom line is Syria has been a fluid battle space and situation for some time, and that certainly hasn't changed now with these latest developments on the ground.

CORNISH: That's NPR's Peter Kenyon.

Peter, thank you.

KENYON: Thank you, Audie.

CORNISH: And, Jane Arraf, thank you for your reporting.

ARRAF: Thank you. Transcript provided by NPR, Copyright NPR.