Israel also provided salaries to rebel fighters, paying each one about $75 a month, and supplied additional money the groups used to buy arms on the Syrian black market, according to the rebels and local journalists.

The payments, along with the service Israel was getting in return, created an expectation among the rebels that Israel would intercede if troops loyal to President Bashar al-Assad tried to advance on southern Syria.

When regime forces backed by Russian air power did precisely that this past summer, Israel did not intervene, leaving the rebel groups feeling betrayed.