Some U.S.-backed opposition groups in Syria are considering allying themselves with al-Qaeda and other extremist groups over fears that a Donald Trump administration will leave them, The Washington Post reports.
Other tactical options include getting more weaponry from other Sunni nations and adopting more traditional guerilla warfare tactics.
Opposition troops have lost a significant amount of territory in the past year. Repeated airstrikes from government allies like Russia have killed many fighters and civilians.
WATCH | Trump has not advocated military engagement against Syrian dictator Bashar al-Assad. During the presidential campaign, he opposed his own vice president-elect, Mike Pence, on that issue.
My attitude was you're fighting Syria, Syria is fighting ISIS, and you have to get rid of ISIS.
He has said his priority is the fight against ISIS, even after Assad named the U.S. a "natural" counterterrorism ally.
Official U.S. estimates suggest at least half a million "moderate opposition" fighters that are not likely to give in.
Meanwhile, current Secretary of State John Kerry is pursuing another cease-fire in Syria after a previous effort failed.
Rep. Adam Schiff (Calif.), the ranking Democrat on the House Intelligence Committee, said there would be "significant reputational costs" if the U.S. abandoned opposition fighters.
U.S. allies like Saudi Arabia and Qatar would not support a U.S. exit, as they believe Iran, which has supported Assad, poses a threat.