People look at the destroyed weapons of forces loyal to Libyan leader Muammar Gadhafi on Wednesday after a coalition air strike on the road between Benghazi and Ajdabiyah. [Photo/Agencies]

BENGHAZI - NATO ships began patrolling off Libya's coast Wednesday as airstrikes, missiles and energized rebels forced Moammar Gadhafi's tanks to roll back from two key western cities.

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 Adm. 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.

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A doctor in Misrata said Gadhafi's tanks fled after the airstrikes, giving a much-needed reprieve to the besieged coastal city. The airstrikes 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.

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. He had no answer when asked about a possible stalemate if Gadhafi hunkers down, and the coalition lacks UN authorization to target him.

Obama, when asked about an exit strategy during an interview with the Spanish-language network Univision, 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."

The administration wants others to lead the way soon: Gates said the US could relinquish control as soon as Saturday. Members of the coalition, however, were still divided over the details.

In a compromise proposal, NATO would be guided by a political committee of foreign ministers from the West and the Arab world. But NATO nations remained deadlocked over the alliance's possible role in enforcing the UN-authorized no-fly zone.

NATO warships, meanwhile, started patrolling Wednesday to enforce the UN. arms embargo against Libya. Alliance spokeswoman Oana Lungescu said the action was to "cut off the flow of arms and mercenaries," activity that intelligence reports say is continuing.

Missiles fired from submarines in the Mediterranean, bombs dropped by B-2 stealth bombers and an array of airstrikes easily totaled hundreds of millions of dollars by the fifth day of the coalition campaign.

Hueber said international forces were attacking government troops. On Wednesday evening, Libyan state television reported a "Crusader colonialist bombing targeting certain civil and military locations" in Tripoli's Tajoura district.

US Secretary of State Hillary Rodham Clinton said Gadhafi can end the crisis quickly _ by leaving power. She said the US wants the Libyan government to "make the right decision" by instituting a cease-fire, withdrawing forces from cities and preparing for a transition.