Three years after the CIA began secretly shipping lethal aid to rebels fighting against Syrian President Bashar al-Assad, battlefield losses and fears that a Donald Trump administration will abandon them have left tens of thousands of opposition fighters weighing their alternatives.

Among the options, say U.S. officials, regional experts and the rebels themselves, are a closer alliance with better-armed al-Qaeda and other extremist groups, receipt of more sophisticated weaponry from Sunni states in the Persian Gulf region opposed to a U.S. pullback, and adoption of more traditional guerrilla tactics, including sniper and other small-scale attacks on both Syrian and Russian targets…

From a slow and disorganized start, the opposition “accomplished many of the goals the U.S. hoped for,” including their development into a credible fighting force that showed signs of pressuring Assad into negotiations, had Russia not begun bombing and Iran stepped up its presence on the ground, said one of several U.S. officials who discussed the situation on the condition of anonymity because they were not authorized to speak publicly.

The United States estimates that there are 50,000 or more fighters it calls “moderate opposition,” concentrated in the northwest province of Idlib, in Aleppo and in smaller pockets throughout western and southern Syria, and that they are not likely to give up.