Throughout the day, no air power was visible overhead. A Pentagon spokesman, Capt. Darryn James, said that American air power had played a smaller role in the war since Sunday, and with command and control of the air campaign officially shifted to NATO, by midnight on Monday in Washington the United States had no strike sorties planned.

American aircraft, Captain James said, would now be on a so-called standby mode and would fly only when requested by NATO and approved by the Pentagon. The withdrawal of American assets means, among other things, that the rebels will have less support from two classes of aircraft that made several successful attacks against the Qaddafi forces in eastern Libya — the AC-130 gunship and A-10 — than when the loyalist forces were turned back just short of Benghazi, the rebel capital, two weeks ago.

The quiet in the eastern skies on Monday seemed to underscore Mr. Essawi’s sentiment that the international military campaign, after initially turning back Colonel Qaddafi’s army and militias as they swept eastern Libya, had lost momentum, leaving adrift the ground war, waged by rebels with virtually no military experience or structure.

“There’s a delay in reacting and lack of response to what’s going on on the ground, and many civilians have died, and they couldn’t react to protect them,” Mr. Essawi said in Rome.