BENGHAZI, Libya - NATO ships began patrolling off Libya's coast as air strikes, missiles and energized rebels forced Muammar Gadhafi's tanks to roll back from two key western cities, including one that was the hometown of army officers who tried to overthrow him in 1993.

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Also on Wednesday, Libya's opposition took haphazard steps to form a government in the east, as they and the US-led force protecting them girded for prolonged and costly fighting. Despite disorganization among the rebels - and confusion over who would ultimately run the international operation - coalition air strikes and missiles seemed to thwart Gadhafi's efforts to rout his opponents, at least for now.

Anti-aircraft fire lit up the sky in Tripoli late on Wednesday, and explosions could be heard. Coalition aircraft hit a fuel depot in Tripoli, a senior government official told reporters at a late-night news conference. Deputy Foreign Minister Khaled Kaim at first denied reports that Gadhafi's compound in Tripoli was hit earlier, then backtracked and said he had no information about that. Other targets on Wednesday were near Benghazi and Misrata, he said.

US Defense Secretary Robert Gates acknowledged there is no clear end to the international military enforcement of the no-fly zone over Libya, but President Barack Obama said it "absolutely" will not lead to a US land invasion.

From Ajdabiya in the east to Misrata in the west, the coalition's targets included Libyan troops' mechanized forces, mobile surface-to-air missile sites and lines of communications that supply "their beans and their bullets", said Rear Admiral Gerard Hueber, a top US officer in the campaign in Libya.

He asserted that Gadhafi's air force has essentially been defeated. He said no Libyan aircraft had attempted to fly over the previous 24 hours.

"Those aircraft have either been destroyed or rendered inoperable," Hueber told Pentagon reporters by phone from the US command ship in the Mediterranean Sea.

A doctor in Misrata said Gadhafi's tanks fled after the air strikes, giving a much-needed reprieve to the besieged coastal city, which is inaccessible to human rights monitors or journalists. The air strikes struck the aviation academy and a vacant lot outside the central hospital, the doctor said.

"Today, for the first time in a week, the bakeries opened their doors," the doctor said, speaking on condition of anonymity for fear of reprisals if Gadhafi's forces take Libya's third-largest city, 200 km southeast of Tripoli.

Neither the rebels nor Gadhafi has mustered the force for an outright victory, raising concerns of a prolonged conflict.

Gates said no one was ever under any illusion that the assault would last just two or three weeks.

Obama, when asked about an exit strategy, didn't lay out a vision for ending the international action, but rather said: "The exit strategy will be executed this week in the sense that we will be pulling back from our much more active efforts to shape the environment."

Associated Press