WASHINGTON -- The Obama administration on Wednesday tried to rein in "loose talk" about military options in Libya, including a "no-fly zone" that the Pentagon chief said would first require attacking Moammar Gadhafi's government.

At the same time, U.S. officials said the North African country risked descending into chaos.

The idea of protective military flights over Libya has gained footing with some in the United States and Europe as a means to prevent Gadhafi from launching aerial attacks on rebels seeking his ouster. But Defense Secretary Robert Gates told lawmakers that a military operation would have to come before creation of a no-fly zone.

"There is a lot of, frankly, loose talk about some of these military options," Gates said at a House Appropriations subcommittee hearing.

"Let's just call a spade a spade: A no-fly zone begins with an attack on Libya to destroy the air defenses."

He added that the operation would require more warplanes than are on a single U.S. aircraft carrier.

"It is a big operation in a big country," he said.

Gates said the Pentagon could get the job done if ordered by the president, but his message was unmistakable. With wars in Afghanistan and Iraq, the military has no interest in getting bogged down in a third one, especially in another Muslim country.

Sen. John Kerry, chairman of the Senate Foreign Relations Committee, said at a hearing attended by Secretary of State Hillary Rodham Clinton that "significant financial commitment by the U.S." was crucial to help what he called a "monumental and uplifting transformation" in the Mideast.

Clinton testified that the U.S. was "taking no options off the table so long as the Libyan government continues to turn its guns on its own people." She said the administration had grave concerns about the instability in the country, but she tempered her tone on a possible no-fly zone.

"One of our biggest concerns is Libya descending into chaos and becoming a giant Somalia," Clinton said.

She said that didn't seem imminently likely. But she noted that many al-Qaida fighters in Afghanistan and Iraq came from eastern Libya, which rebels largely have freed from Gadhafi's control.

Gates and Clinton spoke as the administration considered military options to force Gadhafi to halt violence that has killed an unknown number of civilians. The U.S. and European allies also want Gadhafi to leave power.

Some NATO countries are drawing up contingency plans modeled on the no-fly zones over the Balkans in the 1990s in case there is international support to impose an air embargo over Libya, diplomats said.

NATO has said that any such move would require a clear mandate from the U.N. Security Council. That's unlikely because Russia, which has veto power in the council, has rejected the idea.

The U.S. may need to flex muscle if penalties don't work against Gadhafi, but it doesn't want to provoke an even deadlier response in Libya.

Gadhafi lashed out against Europe and the U.S. pressuring him to step down and promised to "fight until the last man and woman." He said thousands of Libyans will die if U.S. and NATO forces intervene.

Egyptian officials said two U.S. warships passed through the Suez Canal on Wednesday on their way to the Mediterranean Sea, closer to Libya. The amphibious assault ships USS Kearsarge and USS Ponce entered the canal from the Red Sea. The officials, speaking on condition of anonymity because they aren't authorized to talk to media, said the Kearsarge carried 42 helicopters.

Gates had said Tuesday that he ordered the two warships into the Mediterranean, along with an extra 400 Marines, in case they are needed to evacuate civilians or provide humanitarian relief. He made clear he had little enthusiasm for direct military intervention.

Kerry's financial package for the Mideast would be separate from the current spending fight on Capitol Hill.

Protesters in Tunisia and Egypt have chased their longtime leaders from power this year. Demonstrators in Bahrain, Yemen and elsewhere are seeking concrete transitions toward democracy.

"Events this powerful demand a response of equal power," said Kerry, D-Mass. "This is not about sending troops and tanks to remake a region in our image. It is about sending economists and election experts and humanitarian aid to help a region remake itself."

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Associated Press writers Matthew Lee, Donna Cassata and Robert Burns contributed to this report.