The USN has an airbase, NAS Sigonella roughly 300nm from Tripoli and 400nm from Benghazi. (I see parked C-17s, C-135 tankers and P3 Orions:
NAS Sigonella- Google Maps)
Pentagon thoughts: (looks like bombs have to be dropped for a NFZ to done properly)
Pentagon hesitant on no-fly zone over Libya - Wash Post
.... [Gates] "We also have to think about frankly the use of the U.S. military in another country in the Middle East," he told reporters at a news conference. "So we are sensitive about all these things."
.... Gen. James N. Mattis, the head of U.S. Central Command, told a Senate panel that it would be necessary to preemptively attack Libyan air-defense batteries and installations to ensure that they could not shoot down U.S. or NATO planes.
[full quote] “My military opinion is, sir, it would be challenging. You would have to remove the air defense capability, in order to establish the no-fly zone. So it — no illusions here, it would be a military operation. It wouldn’t simply be telling people not to fly airplanes."
Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, echoed Mattis's warning about preemptive strikes on Libyan targets. ...