With NATO's bombing of Libya now in its sixth month, a new sense of urgency is gripping the alliance as two critical deadlines loom next month.
After months of combat stalemate, the insurgents have made dramatic gains in recent weeks. An offensive from their beleaguered enclave in the Nafuz Mountains resulted in the capture of the strategic Mediterranean town of Zawiya and put them within striking distance of Moammar Gadhafi's capital of Tripoli.
The rapid advance offers NATO the chance to bring to a conclusion a campaign that has drawn increasing international criticism and caused serious rifts within the alliance.
NATO officials deny there has been a fundamental shift in tactics in recent days to provide close air support to the advancing rebels, saying they continue to be focused on the protection of civilian populations as mandated by a U.N. Security Council resolution.
But they acknowledge that in response to new developments, alliance bombers are pummeling Gadhafi's troops holding defensive positions around government-held towns and villages, under attack from the advancing rebel forces.
"The persistent and cumulative action of NATO is creating an obvious effect," NATO spokesman Col. Roland Lavoie said Sunday. "Pro-Gadhafi forces are gradually losing their capabilities to command, to conduct and to sustain their actions."
Italian Defense Minister Ignazio La Russa defended NATO's operations, saying its mission is to protect civilians. "Thus all its targets are military targets," La Russa told Sky TG24 TV.
NATO jets have flown nearly 20,000 sorties in the past month, including about 7,500 strike attacks.
A NATO official said that early in the campaign NATO airstrikes focused on preventing Gadhafi's troops from reoccupying rebel-held towns. Such attacks on regime forces destroyed hundreds of tanks, armored vehicles and guns.
But within a few weeks, Gadhafi's soldiers switched tactics, abandoning their vulnerable heavy weaponry in favor of civilian trucks armed with machine guns or recoilless rifles, which proved difficult to identify and destroy from the air.
"Now the rebel offensive has put them on the defensive, and they are again bringing out their tanks and heavy artillery," said the official who could not be named under standing rules.
"This is why we've been attacking them even when they are trying to beat back rebel advances," he said. "We're still protecting civilians because as soon as the rebels push pro-Gadhafi forces from a town, his troops will turn around and shell the place."
But analysts counter that NATO's continued claims of simply protecting civilians strains credulity, saying the direct tactical air support to the ragtag rebel forces is enabling their battlefield victories.
"It was inevitable that the mission would spiral and the interpretation of U.N. resolutions would widen," said Barak Seener, a Middle East expert at the Royal United Services Institute, a British military think tank. "Thus, NATO has bombed government targets, paving the way for rebels to reach Zawiya."
"Protecting civilian populations now means getting rid of Gadhafi," Seener said.
Alliance military planners are racing against a deadline next month, when member states must vote on a second three-month extension of the mission. Approval for an extension may prove problematic, since support for the bombing campaign has eroded among allies who say it detracts resources from NATO's main mission, the 10-year war in Afghanistan.
Also in September, the U.N. General Assembly is due to debate the airstrikes, with many members critical of NATO for overstepping the original U.N. mandate in March which only authorized a no-fly zone and the protection of civilians caught up in the civil unrest.
NATO allies urged Gadhafi on Sunday to step down immediately.
"We hope that this is the turning point," German Foreign Minister Guido Westerwelle said. "We hope that the last days of this unjust regime have begun."
French President Nicolas Sarkozy urged Gadhafi to "spare his people further useless suffering" by stepping down immediately.