Rebel forces bore down Monday on Moammar Gadhafi's hometown of Sirte, a key government stronghold where a brigade headed by one of the Libyan leader's sons was digging in to defend the city and setting the stage for a bloody and possibly decisive battle.
The opposition made new headway in its rapid advance westward through oil towns and along stretches of empty desert highway toward Sirte and beyond to the big prize -- the capital, Tripoli.
But the rebels remain woefully outgunned by Gadhafi's forces, who swept the insurgents from positions in eastern Libya until the international intervention forced government troops to withdraw.
Rebels acknowledged that they could not have held their ground without international airstrikes and cruise missile attacks. Libya state television reported new NATO airstrikes after nightfall, targeting "military and civilian targets" in the cities of Garyan and Mizda about 40 miles and 90 miles, respectively, from Tripoli.
NATO insisted that it was seeking only to protect civilians and not to give air cover to an opposition march. But that line looked set to become even more blurred. The airstrikes now are clearly enabling rebels bent on overthrowing Gadhafi to push toward the final line of defense on the road to the capital.
Vice Adm. William E. Gortney, staff director for the Joint Chiefs of Staff, said the United States was hitting Libyan targets with Thunderbolts and AC-130 gunships, aircraft that can fly low enough to support ground operations.
There was growing criticism from Russia and other countries that the international campaign of air raids is overstepping the bounds of the U.N. resolution that authorized a no-fly zone. The complaints came at a critical transition in the campaign from a U.S. to a NATO command. That threatens to hamper the operation, as some of the 28 NATO member nations plan to limit their participation to air patrols, rather than attacks on ground targets.
Monday, rebel fighters moved about 70 miles west Monday from the coastal oil terminal and town of Ras Lanouf to just beyond the small town of Bin Jawwad, where their push was halted by government fire along the exposed desert highway and the heavily mined entrance to Sirte.
The rebels are currently just 60 miles from Sirte, the bastion of Gadhafi's power in the center of the country.
Take control of that, and there's only the largely rebel-held city of Misrata -- and then empty desert -- in the way of the capital. Sirte could therefore see some of the fiercest fighting of the rebellion, which began Feb. 15.
"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," said Gamal Mughrabi, a 46-year-old rebel fighter. "So Sirte is the last line of defense." He said that there are both anti- and pro-Gadhafi forces inside Sirte.
Sirte, which houses a significant air force and military base, 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 into a city of 150,000 with lavish conference halls.
Amnesty International contended Monday that dozens of Libyans have disappeared in recent days and that they are probably in custody. The human rights group said Gadhafi's supporters appear to have a systematic policy to detain anyone suspected of opposition.
Parents of a Libyan woman who alleged she was detained by Gadhafi's troops and later gang-raped said in interviews aired Monday that their daughter is being held hostage at Gad-hafi's compound in Tripoli.
Iman al-Obeidi made headlines when she rushed distraught into a Tripoli hotel Saturday, seeking to tell foreign reporters about her rape. She was tackled by waitresses and government minders and dragged away from the site in an ensuing melee.