On Saturday, two neighborhoods in the central city of Homs that have come under the sway of the Free Syrian Army were bombarded by government forces in a further sign the chances of imposing a cease-fire soon remain slim.
Residents cowered in basements as shells slammed repeatedly into the city, sending clouds of smoke billowing into the sky, according to videos posted online.
The increased activity comes as an international effort to aid the Free Syrian Army quietly gathers pace. Although the rebels insist they are still not being helped by foreign countries, they say they now have ample access to money from Syrian opposition figures and organizations outside the country and are using it to buy supplies on a revived black market in Syria.
U.S. officials and Syrian opposition figures said last month a discreet effort by Arab Gulf states to channel money and weapons to the rebels - an undertaking the United States is helping to coordinate - had begun to gear up. The rebels' apparent progress suggests the assistance is having an effect, driving the dynamic toward a deepening conflict and perhaps intensifying pressure on the government to make concessions, even as world powers rule out military intervention, analysts say.
The lightly armed rebels, equipped mostly with assault rifles, rocket-propelled grenades, and some mortars, are still a long way from being able to inflict defeat on the superior Syrian army.
The Syrian rebels "are never going to be capable of driving on Damascus and driving out the regime," said Jeffrey White, a former Defense Intelligence Agency official now with the Washington Institute for Near East Policy. But, he said, with their repeated hit-and-run attacks on Syrian outposts and convoys, it is clear "they're increasing pressure on the regime, increasing attrition and increasing defections."
"They're looking stronger to me, and better," White said. "People have been calling them a ragtag force, and I just don't think that's accurate anymore. I would describe them as an increasingly capable guerrilla force."
The government can use overwhelming force against rebel strongholds, but it "can't bring force to bear everywhere at the same time," said Amr al-Azm, a professor of history at Shawnee State University in Ohio who is active in the Syrian opposition.