Late Tuesday, two amphibious assault ships carrying helicopters and 400 U.S. Marines will pass through the Suez Canal into the Mediterranean Sea. But Defense Secretary Robert Gates said they would be used in Libya only for emergency evacuations or to deliver relief supplies.
CBS News national security correspondent David Martin reports Gates has raised a host of reservations about military intervention, including: A lack of authorization from either the U.N. or NATO; A reluctance to tie up forces which might be needed in Afghanistan; and concerns about fanning anti-American sentiment in the rest of the Arab world.
"We also have to think about...the use of the U.S. military in other countries in the Middle East," Gates said.
Gates said he was unable to gauge the rebels' chances of overthrowing Qaddafi.
"It remains to be seen how effectively military leaders who have defected from Qaddafi's forces can organize the opposition in the country," Gates said.
Earlier Tuesday, Secretary of State Hillary Clinton ticked off future scenarios for Libya and two out of three were bad.
"Libya could become a peaceful democracy, or it could face protracted civil war or it could descend into chaos," Clinton said.
The U.S. and Britain are openly talking about setting up a no-fly zone over Libya.
"It is not acceptable to have a situation where Col. Gaddafi can be murdering his own people, using airplanes and helicopter gunships and the like," British Prime Minister David Cameron said.
But China and Russia are likely to oppose any U.N. resolution authorizing a no-fly zone, and Gates has not yet ordered the aircraft carrier Enterprise into the Mediterranean.
Gen. James Mattis, who commands U.S. forces in the Middle East, cautioned that patrolling Libyan air space would require knocking out Libyan air defense missiles on the ground.
"(I have) no illusions here," Mattis said. "It would be a military operation. It wouldn't simply be telling people not to fly airplanes."
The U.S. military knows all about no-fly zones. It ran them over Iraq for more than a decade, but it took an invasion to get rid of that dictator.
Martin reports that the U.S. already had one guided missile destroyer in the Mediterranean, and has now sent a second one. The Pentagon, meanwhile, is looking at three basic options:
First, jam Libya's communications so that Qaddafi has a hard time communicating with his forces. Second, send those Marines ashore to set up aid stations for the rebel areas. And third, establish a no-fly zone so that Qaddafi cannot use his air force against his own people.
One thing that is not an option for the Pentagon: The U.S. taking on
Sanctions against Qaddafi's government have been enacted to squeeze them financially and to cut off the flow of arms to the regime. U.S. Ambassador to the United Nations Susan Rice said on "The Early Show" this morning that Qaddafi must be shown that "the international community is not going to tolerate the slaughter of innocents.
"So we are continuing contingency planning with NATO allies and others for all sorts of options that may be necessary."
"There could be a real humanitarian disaster in Libya as this situation unfolds," Rice told "Early Show" anchor Erica Hill. "And if that is to occur, we and others in the international community would want to be prepared to respond if necessary, promptly and effectively."