U.S. and allied forces prepared to conduct military operations against Libya after the United Nations Security Council authorized international action to prevent Libyan leader Moammar Kadafi from using indiscriminate slaughter to quell a monthlong revolt.
With the outgunned rebels in retreat, the council on Thursday authorized "all necessary measures" to protect civilians, giving its blessing to attacks on Libyan aircraft and ground forces now encircling the final opposition stronghold of Benghazi.
"Today, the Security Council has responded to the Libyan people's cry for help," Susan Rice, the U.S. ambassador to the United Nations, said after the vote.
She said the resolution became necessary because "Kadafi and those who stand by him continue to grossly and systematically abuse the most fundamental human rights" despite earlier U.N. sanctions. "Today's resolution is a powerful response … to the urgent needs on the ground."
Pentagon officials, noting that they and European allies have warships and aircraft positioned nearby, said military operations could begin quickly. While officials said that it might take a week to mount a full no-fly zone, surgical strikes could begin before that.
At the same time, U.S. officials cautioned that the U.S. and allies intended to limit their involvement, allowing no "boots on the ground."
Kadafi lashed out in anticipation of the vote, warning that Libya would mount terrorist attacks across the Mediterranean for years if foreign powers took up arms against him.
"If the world gets crazy, we will get crazy," declared Kadafi, who said he was ordering his forces to attack Benghazi on Friday.
In Tripoli, some reacted with shock at the news that the council had authorized military intervention to protect what government supporters describe as armed insurgents.
"Civilians holding guns, and you want to protect them? It's a joke," said Mohammad Salah, a 32-year-old dentist who has been serving as a volunteer translator for Western reporters in the capital. "We are the civilians. What about us?"
"This decision is not good," said a consultant who asked that his name not be used. "It means more blood and more war. It will be like Iraq again. Many people will be killed on both sides. You have to have dialogue and discussions."
But Libya's deputy foreign minister, Khaled Kaim, told reporters early Friday that he did not think there would be airstrikes. He said the government welcomed the language in the resolution that called for protecting civilians and maintaining the country's territorial integrity.
He also warned other countries against arming the rebels.
Meanwhile, the sky over Benghazi was ablaze with celebratory fireworks as news of the U.N. vote spread. And in the seaside eastern city of Tobruk, rebels fired rifles, boys climbed to rooftops, families danced and young men sped through streets with flags flapping out of windows to celebrate the vote.
It was a stunning, joyous scene in rebel territory where people in recent days had become distraught and angry with the international community for not helping to stop the Libyan leader's air attacks on cities and towns. The U.N. vote instantly turned bitterness and fear into a sense of impending victory.
"We will go to Benghazi and then march to Tripoli," said Abdullah Uma, holding a shotgun while driving a car loaded with young, cheering men. "Kadafi is done."
The Obama administration and many allies have been deeply reluctant to embark on military action as the uprising unfolded, fearing a plunge into another uncertain military involvement in a Muslim land. But U.S. officials, as well as those of key allies, have grown increasingly worried that the uprising could end in a humanitarian disaster.
A senior U.S. official said the administration had hoped that the Libyan uprising would evolve "organically," like those in Tunisia and Egypt, without need for foreign intervention.
"Everyone hoped that would be the case here, and no one could say that the U.S. was behind it," he said. "But when … it looked like there might be an imminent slaughter, there was a responsibility on the part of the international community not to let it happen."
The administration had decided that it would not become involved except with U.N. blessing, broad international participation and agreement by Arab nations that they would play an active part, to dispel perceptions that the U.S. was again intervening to protect its oil supplies. On Saturday, the Arab League voted to accept an international no-fly zone.
Since then, officials said, they have been laying the diplomatic and military groundwork for action.
Even so, many diplomats remained cautious about whether the moves would be effective, or come soon enough.
Some diplomats suggested privately that the last-minute diplomacy could also be aimed, at least in part, at giving political cover to the Obama administration and other governments that are facing criticism that they have not mobilized quickly enough against a leader treated as an international pariah for decades.
Secretary of State Hillary Rodham Clinton, speaking to a crowd in Tunisia, said: "We want to support the opposition who are standing against the dictator. This is a man who has no conscience and will threaten anyone in his way."
She predicted that Kadafi would do "terrible things" to Libya and other countries because "it's just in his nature."
The prospect of American military involvement was greeted with enthusiasm and worry in Congress.
In a hearing, Sen. John F. Kerry (D-Mass.), chairman of the Senate Foreign Relations Committee, urged quick action, while Sen. Lindsey Graham (R-S.C.) emerged from a classified briefing declaring that "I learned it's not too late."
But Richard G. Lugar (R-Ind.) and Jim Webb (D-Va.) warned of unpredictable consequences.
"These things are easily begun and often very difficult to end," Webb said.
The U.N. resolution declares that humanitarian relief, not aid for the rebels, is the aim of military action. But U.S. officials contend that U.N. action could immediately help the rebels by giving them reason to hang on in the face of growing odds.
It may also prevent a panicked exodus of civilians in eastern Libya, which could also contribute to a humanitarian disaster.
The council voted 10 to 0, with five abstentions, for the resolution. Germany, China, Russia, India and Brazil abstained.
Staff writers Peter Nicholas, Ken Dilanian, Lisa Mascaro and Christi Parsons in Washington, Tina Susman in New York, Jeffrey Fleishman and David Zucchino in Tobruk, Libya, and Borzou Daragahi in Tripoli, Libya, contributed to this report.