U.S. officials all but admit that no-fly zone is an empty threat

But officials in Washington and elsewhere said that direct military action remained unlikely, and that the moves were designed as much as anything as a warning to Colonel Qaddafi and a show of support to the protesters seeking to overthrow his government…

Privately, American officials said any United States military presence could undermine the legitimacy of the Libyan revolt as an internal, grass-roots movement. Qaddafi supporters — and even those across the Arab world who do not like the dictator — could denounce American action as being only about oil…

Indeed, there is an element of gunboat diplomacy to the talk of military action. Besides reassuring protesters, a senior American official said, the naval vessels and warplanes could be used as a show of force to embolden members of Colonel Qaddafi’s military to turn on him. The announcement of American military planning could have an impact even without carrying out any operations, the official said.