By Andrew Quinn and Mark Hosenball
WASHINGTON (Reuters) - President Barack Obama gave Muammar Gaddafi an ultimatum on Friday -- comply with U.N. demands for a cease-fire or face military action as Washington moved towards risky direct involvement in Libya's turmoil.
Obama, laying out the rationale for deeper U.S. involvement in Libya, said the United States would work with its partners to enforce U.N. demands but promised that no U.S. ground troops would be deployed in the oil-producing North African country.
Although Obama has called on Gaddafi to leave, he stressed the United States would not use its power beyond a well-defined goal: "specifically the protection of civilians in Libya."
Obama called on the Libyan leader to withdraw his forces in the eastern part of the country, where they threaten to overwhelm opposition strongholds such as Benghazi.
"All attacks against all civilians must stop," Obama said in his first public comments on the crisis since the U.N. Security Council voted on Thursday to authorise a "no-fly" zone and other steps to help rebels under attack.
"These terms are not subject to negotiation. If Gaddafi does not comply with the resolution, the international community will impose consequences," Obama said, adding that Gaddafi must also reconnect gas, water and power supplies to rebel-held towns.
Facings deep misgivings among military planners and lawmakers over any Libyan engagement, Obama said he was driven by deep concern that Gaddafi could commit atrocities if allowed to quash the rebellion, which could further destabilize the entire Middle East.
"The United States did not seek this outcome. Our decisions have been driven by Gaddafi's refusal to respect the rights of his people and the potential for mass murder of innocent civilians," he said.
Obama underscored that the United States was working with key European allies as well as Arab countries, hoping to dispel fears that the United States was embarking on a risky adventure without adequate backing.
He is sending Secretary of State Hillary Clinton to Paris on Saturday to take part in an international meeting on the next steps on Libya.
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Clinton said earlier the immediate goal was stopping violence against civilians but the long-term objective was to see Gaddafi depart, although Obama himself did not mention this in his remarks.
"We don't know what the final outcome will be," Clinton said. "The first and overwhelmingly urgent action is to end the violence," she said. "We do believe that a final result of any negotiations would have to be the decision by Colonel Gaddafi to leave."
Obama's comments came after a closed-door meeting with key lawmakers, some of whom have voiced concern the United States was lurching towards involvement in another open-ended conflict in a Muslim country amid a period of unprecedented turmoil across the Middle East.
The shift towards a tougher U.S. stance in favour of military action followed an extended internal debate within the Obama administration over how to stop Gaddafi from routing rebels fighting to end his four-decade rule.
A European national security official told Reuters that one of the most important decision points in both U.S. and European deliberations was a meeting at the White House on Monday involving Obama and senior national security advisers.
Until that meeting, the European official said, almost all of the discussions between Washington, its allies and other members of the United Nations Security Council had been limited to discussion of the establishment of a possible no-fly zone.
At the Monday meeting, however, the U.S. officials came up with an additional provision -- a "no-drive" ban requiring Gaddafi to stop ground movements of his forces.
With Gaddafi's forces pressing their advantage against the beleaguered opposition, the United States on Wednesday abandoned early caution over calls to impose a no-fly zone and pushed hard at the U.N. Security Council for the broader mandate that officials said could include air strikes on Libyan tanks and artillery.
Pentagon officials said they were ready to act on Libya orders but declined to discuss possible operations. U.S. officials announced they would deploy additional amphibious ships to the Mediterranean as part of plans for responding to situation in Libya.
The Obama administration faces doubts both in Congress and among military planners, over the wisdom of involvement in Libya with U.S. forces already fighting a war in Afghanistan and engaged in Iraq.
A U.S. national security official familiar with military planning and operations said there was enormous resistance among military commanders to U.S. involvement in any kind of operation against Gaddafi's forces in Libya.
"The Pentagon does not want to get involved in this," said the official, who is familiar with recent discussions about a possible Libya operation which have been taking place in both Washington and among commanders in the region.
The official said that commanders were asking the Obama administration, "What do you want to get out of this?" but had not gotten a clear answer.
(Additional reporting by Steve Holland, Caren Bohan, Patricia Zengerle and Missy Ryan; Editing by Paul Simao and Eric Walsh)