The United States partnered with the Kurdish-led Syrian Democratic Forces (SDF) in a coalition to defeat IS, and Kurdish groups took control of most of northeast Syria in the campaign.

But Ankara views the SDF and its allies as terrorist groups due to their links to insurgents fighting for Kurdish self-rule in Turkey. When U.S. President Donald Trump complied with Turkey’s demands to pull troops out of Syria last October, Turkish President Recep Tayyip Erdogan launched a military operation, quickly clearing the SDF from border areas.

After declaring a full withdrawal from Syria in a tweet, Trump was persuaded to reverse his decision and left hundreds of troops in the remaining Kurdish-held areas, where he said they would stay to “defend the oil”. It is in these areas that U.S. forces have come under attack, soldiers deployed in Syria told NPR.

"In the last 48 hours we've had two attacks on critical petroleum infrastructure," said one of the soldiers, Captain Alex Quataert.

While the soldiers come under attack from Syrian government militias, they also say they fear the damage that could be caused by ISIS, which remains in the region as a guerrilla force despite losing all of the territory it controlled.

Adding more complexity to the situation is the presence of the Russian military, which is a main backer of Syrian President Bashar Assad. Russian military patrols use the same highways as U.S. forces and frequently harass U.S. vehicles, NPR said.

Meanwhile, drones buzz overhead and, in some instances, attempt to drop mortars on the U.S. troops. Their Kurdish allies blame Turkey, which showed its formidable drone capabilities in a military confrontation with Assad’s forces in northwest Syria earlier this month, but the U.S. troops say the drones likely belong to the Syrian government.

Reporter’s code: 50101