U.S. officials said the decision ended a monthslong debate over the role the American military should play in supporting its few allies on the battlefield in Syria. Administration officials had been deeply concerned that defending the Pentagon-backed force could inadvertently open the first open conflict with the Assad government, which has denounced the U.S. program.

Though the new rules allow Pentagon strikes to defend the U.S.-allied force against any regime attacks, U.S. military officials played down the chances of a direct confrontation, at least in the near term. The newly trained force has committed to fighting Islamic State, not the regime, and won’t be fielded in areas the regime controls. U.S. officials say they believe the regime won’t challenge the new force.

Alistair Baskey, a White House National Security Council spokesman, declined to comment on the specifics of the new rules of engagement. But he said the administration has made clear it will “take the steps necessary to ensure that these forces could successfully carry out their mission.” U.S. support to the Pentagon-trained force, he added, would include “defensive fires support to protect them.”