The Obama administration – blindsided by the speed of Moscow’s direct intervention and a Russian target list that included CIA-trained fighters – made clear on Thursday that the it had no desire to increase the risk of an air clash between the former Cold War foes.

While Washington took pains to insist it still considered the “moderate” opposition vital to Syria’s future and was not abandoning them, withholding U.S. air cover could further jeopardize beleaguered rebel forces.

President Barack Obama has rarely launched military action in support of the opposition in four years of Syria’s civil war and is hesitant to get further ensnared in the conflict. Even if he wanted to, he could face legal limitations due to the scope of his presidential war powers.