BEIRUT -- Syrian forces pummeled the outskirts of Damascus with artillery and airstrikes Friday, anti-government activists reported, apparently in an effort to insulate the city -- the cornerstone of President Bashar Assad's rule -- from rebels who have pushed deeper into a semicircle of suburbs along the city's eastern and southern edges.
Foreign airlines suspended flights into Damascus International Airport for a second day as the air force bombarded rebels along the airport road. Rebels clashed with government forces along the road, lobbing a mortar onto a bridge, activists reported.
Holding Damascus, the capital, is crucial for the government, which keeps its highest concentration of troops and its most loyal and best-trained units in and around the city. Although rebels were unlikely to be able to overrun Damascus soon, analysts said, the encroachment of fighting there -- particularly at the airport -- has a profound psychological effect on government supporters, making them feel trapped. It also forces the military to pull resources from other areas to defend the capital.
Damascus residents reached by phone and by Skype reported hearing explosions and seeing billowing smoke in the distance, and they described an atmosphere of tension and fear. Government checkpoints were so numerous that it was difficult to travel anywhere without passing through one.
Activists reported that violence had spilled into areas that had usually been calm. A mortar shell landed on Baghdad Street, a downtown thoroughfare, killing a 22-year-old man, said Salam Mohammed, an activist in Damascus. There were clashes at Mezze Airport, west of the capital, near a wealthy pro-government area that had usually been isolated from fighting, another activist said.
Emile Hokayem, an analyst at the International Institute for Strategic Studies, described the fighting as "part of the strategy of encirclement of the city."
"The rebels are making a very strong point: that they can go after anything that is seen as critical infrastructure," Mr. Hokayem said, adding that while the government would be able to reopen the airport and the airport road, "the cost of doing so is only going to increase over time."
Fighting has plagued the Damascus suburbs throughout the 20-month conflict, and rebels have tried several times to push into the city. Most recently, they held the southern neighborhood of Medan for several days over the summer. The government responded by moving forces from other areas to Damascus, analysts said, and there were indications that it had also done so in recent days. Activists reported that government forces had withdrawn from one of their last bases in the remote eastern province of Deir al-Zour, leaving rebels in control of oil fields there.
There was less detailed information than usual about the conflict Friday because Internet access was cut to the entire country for a second day, in what seemed to be a government effort to disrupt the communications of its opponents, although some activists and other residents used the Web through satellite services.
Fighter jets bombarded neighborhoods in Daraya, south of the capital, and in East Ghouta, to the east, and artillery pounded other areas in the crescent of territory where rebels have been trying to consolidate gains.