BIN JAWWAD, Libya (AP) -- Rebel forces on Monday fought their way to the doorstep of Moammar Gadhafi's hometown of Sirte, a key government stronghold guarding the road to the capital Tripoli, their rapid advance built on powerful international airstrikes that have battered Gadhafi's air force, armor and troops.
The Skanner News Video: Libyan Rebels Advance on Sirte
The rebels' offensive has restored to the opposition all the territory they lost over the past week and brought them closer than ever to Sirte, with their fighters advancing to within 60 miles (100 kilometers) of the bastion of Gadhafi's power in the center of the country.

But the advance on Sirte and the flip-flop in the conflict's momentum brought into sharper relief the central ambiguity of the international mission in Libya. When Gadhafi's forces were besieging rebel-held cities in the east last week, allied airstrikes on his troops more directly fit into the U.N. mandate of protecting civilians. But those same strikes have now allowed rebels to go on the assault.

Russia on Monday criticized the international campaign, saying it had overstepped its U.N. mandate to protect civilians and had taken sides in a civil war.

NATO's commander for the operation, Lt. Gen. Charles Bouchard of Canada, said his mission was clear, saying every decision was designed to prevent attacks on civilians. "Our goal is to protect and help the civilians and population centers under the threat of attack," he said.

But in Brussels, NATO spokeswoman Oana Lungescu noted that the allied operation was launched in response to "the systematic attacks by Col. Gadhafi against his own people."

"That is how this all started, we have to remember that," she said.

Some residents were fleeing Sirte, as soldiers from a brigade commanded by Gadhafi's son al-Saadi and allied militiamen streamed to positions on the city's outskirts to defend it, witnesses said. Sirte - where a significant air and military base is located - was hit by airstrikes Sunday night and Monday morning, witnesses said, but they did not know what was targeted.

The city of 100,000 is crucial both for its strategic position and its symbolic value. Over the years, Gadhafi has made it effectively Libya's second capital, building up what had been a quiet agricultural community with lavish conference halls where Arab and African summits were held. The city is dominated by members of the Libyan leader's Gadhadhfa tribe, but many in another large Sirte tribe - the Firjan - are believed to resent his rule, and rebels are hoping to encourage them and other tribes there to rise up to help in their capture of the city.

Its fall to the rebels would largely open their way to move on the capital, Tripoli, 250 miles (400 kilometers) to the northwest along the Mediterranean coast.

About halfway between the two lies Libya's third largest city, Misrata, which has been in rebel hands since early on in the nearly month-and-a-half-old uprising but has been under heavy siege by Gadhafi forces for weeks. Misrata came under renewed heavy shelling on Monday, witnesses said. There is little but empty desert highway and a few small hamlets between Sirte and Misrata.

Gamal Mughrabi, a 46-year-old rebel fighter, said there are both anti- and pro-Gadhafi forces inside Sirte and predicted a tough fight. "Gadhafi is not going to give up Sirte easily because straightaway after Sirte is Misrata, and after that it's straight to Gadhafi's house," he said. "So Sirte is the last line of defense."

In a symbolic diplomatic victory for the opposition, the tiny state of Qatar recognized Libya's rebels as the legitimate representatives of the country - the first Arab state to do so.

Libya's rebels have recovered hundreds of miles (kilometers) of flat, uninhabited territory at record speeds after Gadhafi's forces were forced to pull back by the strikes that began March 19. When the first strikes were launched, regime troops were deep in the rebel-held territory, storming toward the opposition capital of Benghazi, 370 miles (more than 600 kilometers) east of Sirte.

A rebel commander among the fighters advancing on Sirte acknowledged that their offensive would not have been possible without the strikes, which he said had evened the two sides' firepower.

"Now because of NATO strikes on (the government's) heavy weapons, we're almost fighting with the same weapons, only we have Grad rockets now and they don't," said Gen. Hamdi Hassi at the small town of Bin Jawwad, just 18 miles (30 kilometers) from the front.

The U.S. launched six Tomahawk missiles Sunday and early Monday from navy positions in the Mediterranean Sea, two defense officials said Monday on condition of anonymity because they were not yet authorized to release the information.

That brought to 199 the number of the long-range cruise missiles fired by international forces in the campaign, one official said.

International air forces flew 110 missions late Sunday and early Monday - 75 of them strike missions. Targets included Gadhafi ammunition stores, air defenses and ground forces, including vehicles and tanks, a third official said.

Hassi said there was fighting now just outside the small hamlet of Nawfaliyah, 60 miles (100 kilometers) from Sirte and scouting parties had found the road ahead to be heavily mined.

He added that the current rebel strategy was to combine military assault with an attempt to win over some of the local tribes loyal to Gadhafi over to their side.

"There's Gadhafi and then there's circles around him of supporters, each circle is slowly peeling off and disappearing," Hassi said. "If they rise up it would make our job easier."

Hundreds of residents, mainly women and children, fled Sirte - some fleeing to the town of Bani Walid about 150 miles west (250 kilometers), said Hassan al-Drouie, a Libyan in exile in France in contact with family members in Sirte who were among those who fled. Some members of Gadhafi's tribe in Sirte fled to another of his strongholds, the city of Sebha, deep in Libya's southwestern deserts, said another Libyan in exile, Abdel-Rahman Barkuli, who cited his relatives in Sebha.

Some men had remained in Sirte and had taken up weapons to protect their homes - but not to fight alongside Gadhafi's troops against the rebels, said al-Drouie. He said the al-Saadi Brigades headed by Gadhafi's son have taken up positions on the city's southern and eastern entrances.

International airstrikes also hit Sebha, 400 miles (650 kilometers) south of Tripoli. The area remains strongly loyal to Gadhafi and is a major transit point for ethnic Tuareg fighters from Mali and Niger fighting for the government. The state news agency JANA said the strikes destroyed a number of houses. Britain's Defense Ministry announced Monday that its Tornado aircraft had attacked ammunition bunkers around Sebha.

A rebel push into the west would deeply complicate the conflict. The east of the country shook off nearly 42 years of Gadhafi's rule in a series of popular demonstrations starting in mid-February and inspired by similar successful uprisings in Egypt and Tunisia.

Several cities in the west also rose up - including Zawiya, Zwara, Sabratha and others - but each was subsequently crushed by Gadhafi's forces, often bloodily. In Zawiya, for example, a still unknown number of people were killed in a brutal siege by Gadhafi's forces that lasted more than a week and reportedly included heavy shelling of civilian areas. Regime militiamen also squashed attempts at protests in Tripoli.

Anti-Gadhafi sentiment is believed to still be widespread in many of those areas, but they are mixed together with regime supporters in some places.

Gadhafi is not on the defensive everywhere. His forces continued to besiege Misrata, the main rebel holdout in the west. Residents reported fighting between rebels and loyalists who fired from tanks on residential areas.

Rida al-Montasser, of the media committee of Misrata, said that nine young men were killed and 23 others wounded when Gadhafi brigades shelled their position in the northwestern part of the city on Sunday night. He also said that the port was bombed.

Turkey's Anatolia new agency said a Turkish civilian ferry carrying 15 medics, three ambulances and medical equipment was heading for Misrata to help treat some 1,300 people injured in attacks there.

Libya accused NATO of becoming directly involved in the fighting.

"This is the objective of the coalition now, it is not to protect civilians because now they are directly fighting against the armed forces," Khaled Kaim, the deputy foreign minister, said in the capital, Tripoli. "They are trying to push the country to the brink of a civil war."

His position found some support in Russia, where Foreign Minister Sergey Lavrov said strikes on Gadhafi's forces would amount to interference in what he called Libya's civil war, and thus would breach the U.N. Security Council resolution that envisaged a no-fly zone only to protect civilians. The council mandate, however, goes beyond a no-fly zone to allow "all necessary measures" to protect civilians.

After retaking two key oil complexes east of Sirte in the past two days, rebels promised to quickly restart Libya's stalled oil exports, prompting a slight drop in the soaring price of crude oil to around $105 a barrel.

The tiny Persian Gulf state of Qatar, however, has formally recognized the rebels as the legitimate representatives of the country and promised to help them sell their crude oil on the international market.

Qatar has been well ahead of other Arab countries in embracing the rebels and is also participating in the U.N.-mandated no-fly zone over Libya.