RACHEL MARTIN, HOST:
In Syria, two factions that have worked with the U.S. in the fight against ISIS recently turned on each other. The U.S. tried to calm the tensions using diplomacy, sending in troops in armored vehicles flying American flags. But NPR's Alison Meuse reports the rivalry has not subsided.
ALISON MEUSE, BYLINE: The U.S. works with several factions in Syria's civil war to fight against ISIS. One of them is dominated by ethnic Kurds. Another is supported by Turkey. I reached Shervan Darwish from the Kurdish-led group describing how Turkish-backed fighters attacked his turf in recent weeks.
SHERVAN DARWISH: (Through interpreter) They used a very big force and intense tank shelling. In one day, they used more than 1,500 artillery shells and rockets on a single village.
MEUSE: Factional fighting in Syria is nothing new. But for the U.S., this presents a problem. These are the men and women they hope to work with to retake the city of Raqqa from ISIS. They needed to stop them fighting each other, so American Humvees flying the Stars and Stripes rolled through that Kurdish-held territory, the town of Manbij, to deter the Turkish-backed factions. Darwish was pleased.
DARWISH: (Through interpreter) The increase of forces in Manbij was reassuring for people. And it confirmed that Manbij and its surrounding areas are under the protection of the international coalition.
MEUSE: But it's probably only a temporary hiatus in the feud, which will only intensify as the forces get closer to Raqqa. Both factions believe they should be the ones to take it.
I speak with Colonel Haitham Afisee who commands one of the Arab rebel groups that's supported by the U.S. and Turkey but has opposed the Kurdish-led alliance. He says those Kurdish-led forces are trying to take part of Syria for themselves and will never be welcomed in Raqqa.
HAITHAM AFISEE: (Through interpreter) Raqqa is Arab, and it won't be anything except Arab.
AFISEE: Afisee says he's waiting for an international deal to be brokered to allow his men to proceed to Raqqa unhindered. Such a deal is not going to come easy.
Nicholas Heras, a Syria analyst at the Washington-based Center for a New American Security, has been monitoring deliberations in the Trump White House regarding Raqqa. He says the U.S. military trusts its Kurdish-led partners in Syria, known as the Syrian Democratic Forces or SDF.
NICHOLAS HERAS: The special operators on the ground, the guys that are being asked to go and to engage with these Syrian partner forces - they are all-in on the SDF. They believe it can get the job done. In a sense, the SDF is the child of U.S. Special Forces. That is an important component of this discussion.
MEUSE: But the Kurds in the SDF are linked to Kurdish separatists in Turkey, and Turkey sees them as terrorists. The U.S. has to balance its support for the Kurds with its need to keep on good terms with Turkey and maintain access to Turkish air bases. In the meantime, it's not clear who will push ISIS out of Raqqa.
Alison Meuse, NPR News, Beirut.
(SOUNDBITE OF ERNEST GONZALES' "WHILE ON SATURN'S RINGS") Transcript provided by NPR, Copyright NPR.