Islamist forces this weekend overran key facilities which until then had been controlled by the more moderate Western-backed Free Syrian Army (FSA), seizing warehouses containing U.S. military gear sent to the FSA and forcing the group’s commander Gen. Salim Idris to flee the country. Buzzfeed had reported on Tuesday that Washington had abruptly suspended direct U.S. assistance to opposition-controlled areas northern Syria.

The suspension comes in response to a worrisome development for the Free Syrian Army, or FSA, the moderate rebel coalition backed by the U.S. and its western allies. The FSA has been losing ground steadily to hardline rebel factions, including local affiliates of Al-Qaeda and a powerful rival coalition called the Islamic Front. On Friday, Islamic Front fighters overtook several key FSA headquarters and warehouses in Atimeh, a town near the Turkish border, dealing the FSA a bracing blow — and drawing alarm from the U.S. “We are obviously very concerned,” the U.S. official said in emailed comments, requesting anonymity because of the issue’s sensitivity. “As a result of this situation, the United States has suspended all further deliveries of non-lethal assistance into northern Syria.”

The Wall Street Journal yesterday reported out portions of the story, detailing some of the FSA’s losses and revealing that Idris’s headquarters were among the facilities seized by the Al Qaeda-linked Islamists.

The turn of events was the strongest sign yet that the U.S.-allied FSA is collapsing under the pressure of Islamist domination of the rebel side of the war. It also weakened the Obama administration’s hand as it struggles to organize a peace conference next month bringing together rebels and the regime…Gen. Idris flew to the Qatari capital of Doha on Sunday after fleeing to Turkey, U.S. officials said Wednesday. “He fled as a result of the Islamic Front taking over his headquarters,” a senior U.S. official said.

Earlier this week the Daily Beast’s Josh Rogin assessed that facts on the ground had already forced the Obama administration to “to reach out to the very Islamist groups it once hoped to marginalize.”

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