BIN JAWWAD, Libya — 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.
Libya state television reported new NATO airstrikes after nightfall, targeting "military and civilian targets" in the cities of Gharyan 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 Gortney, staff director for the Joint Chiefs of Staff, said the United States was hitting Libyan targets with A-10 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 air campaign is overstepping the bounds of the U.N. resolution that authorized it. 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.
The rebels are 60 miles from Sirte, the bastion of Gadhafi's power in the center of Libya.
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 on Feb. 15.
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 was hit by airstrikes Sunday night and Monday morning, witnesses said, but they did not know what was targeted.
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 help them.
Pentagon officials are looking at plans to expand the firepower and airborne surveillance systems, including using the Air Force's AC-130 gunship armed with cannons that shoot from the side doors, as well as helicopters and drones. That weaponry might allow for more precision in urban fighting, while drawing forces closer to the combat.
NATO's commander for the operation, Lt. Gen. Charles Bouchard of Canada, insisted 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.
Amnesty International charged Monday that dozens of Libyans have disappeared in recent days, and 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 to his rule.