Panetta called the NATO intervention a "remarkable achievement" and hailed the fall of Moamer Kadhafi's regime after talks Thursday with fellow NATO defence ministers in Brussels.

The Pentagon chief told a news conference that NATO allies were weighing when to halt the bombing campaign and that it would depend in part on the strength of local forces on the ground, who have encircled Kadhafi's loyalists.

Panetta would hold talks with Canadian Lieutenant General Charles Bouchard, who is running the Libya air operation, and US Admiral Samuel Locklear, head of allied joint force command in Naples, officials said.

NATO Supreme Allied Commander in Europe, US Admiral James Stavridis, based in Mons, Belgium, was also scheduled to join in the discussions.

Speaking to reporters earlier on his trip, Panetta said he also wanted to express appreciation to US and allied officers at the Naples command for their role in what he called a "successful" operation.

"I want to thank the operations people that work there in Naples," Panetta said. "They did a great job."

After knocking out air defence sites in Libya at the outset of the campaign, the US military assumed a low-profile role in the NATO operation with the British and French taking the lead.

The United States, which carried out about a quarter of all sorties in the six-month campaign, provided crucial support in the form of airborne refuelling of fighter aircraft, surveillance planes -- including unmanned robotic drones -- and specialists to draw up bombing targets.

The United States conducted about 75 percent of all refuelling missions and 70-80 percent of all surveillance and reconnaissance flights, US officials said.

The American military currently has more than 70 aircraft deployed in the operation and more than 7,000 personnel have taken part, officials said.

The Libya campaign offers a stark contrast to the Kosovo war in 1999. In Libya, European and Canadian aircraft dropped 95 percent of all precision guided munitions while in Kosovo, 95 percent of all munitions were launched by US pilots, a senior NATO diplomat said.

With Moamer Kadhafi diehards surrounded by the new leadership's forces in Sirte and Bani Walid, and the fallen Libyan leader in hiding, the number of NATO air strikes has drastically declined in recent weeks.

NATO officials say the six-month-old air war will continue as long as Kadhafi loyalists pose a threat to civilians.

"Sirte is extremely symbolic. But it is important that we no longer have pockets of resistance," said French Defence Minister Gerard Longuet.

"Whether Kadhafi disappears from the scene is important, but it's not enough," Longuet told reporters before a second day of talks with NATO counterparts.

NATO Supreme Allied Commander in Europe, US Admiral James Stavridis, recommended to the ministers late Wednesday that the mission continue until the new regime consolidates control of the entire country, diplomats said.

Once the country is deemed secure, Stavridis suggested that the no-fly zone carry on for two weeks until NATO is "sure that fighting has ended," the diplomat told AFP on condition of anonymity.

Kadhafi loyalists have made it tricky for NATO warplanes to bomb them by hiding in built-up areas, using civilians as human shields to deter air strikes, officials said.

NATO reported eight air strikes in Bani Walid, a southern desert town, on Wednesday but no bombings in Kadhafi's hometown of Sirte in the east, compared to between 15 and 20 raids daily across Libya earlier in the mission.

The campaign began in March when Kadhafi troops had rebels on the back foot. NATO's strikes helped tip the balance in favour of a loose coalition of opponents who in August overran the capital Tripoli , winning international recognition.

NATO Secretary General Anders Fogh Rasmussen said the decision to halt the operation would hinge on the ability of National Transitional Council (NTC) forces to maintain order -- not on the fate of Kadhafi.

"The termination of the operation is not dependent on Colonel Kadhafi," he told reporters on Wednesday.

Officials said the alliance had to make a political judgement, balancing the need to prevent attacks on civilians while avoiding the impression of meddling.

"It will be a political decision, which will involve the UN and the NTC and it will be a question of an international concert of opinion that the time has come," said a senior NATO official.

"The big risk is that one day we stop and the next day there is a massacre, in which case we would have failed."

Senior military officers overseeing the operation from Naples, Italy, were increasingly eager to call an end to the effort given the retreat of Kadhafi's troops, officials said.

But alliance members are waiting for a clear conclusion to fighting in Sirte and Bani Walid, where NTC troops are trying to finish off Kadhafi loyalists.

Success in Afghanistan, a war marking its 10th anniversary on Friday, also depends on the ability of local forces to ensure security for the population.

NATO is gradually handing control of the battlefield to Afghan forces, with the goal of withdrawing foreign combat troops from the country by 2014. Some 140,000 NATO soldiers are in Afghanistan, including 100,000 Americans.

Efforts to find a peaceful end to the war with the Taliban were dealt a major blow last month when former president Burhanuddin Rabbani, the government's peace envoy, was killed by a suicide bomber.

"Transition is on track and it will not be derailed," Rasmussen said. "To those who only offer death and destruction to the Afghan people, we say, 'you will not triumph'."