BEIRUT - A new rebel offensive around the Syrian capital has demonstrated the insurgents' strengths after six months of combat in the Damascus region. But from afar it's hard to gauge how close the rebels are to penetrating the central city or to capturing and holding new ground.

As in the country's north, the rebels around Damascus have made gains against government bases, capturing weapons and demonstrating an ability to shoot down some of the government's aircraft. But their advance has been slow in areas that are loyal to the regime, and the government's advantages of artillery and air power remain important factors in slowing the rebels.

Insurgents forced the closure of the Damascus airport, which lies several miles outside the city, last week for the first time. But the extent to which the fighting affected the airport itself -- or merely the road leading to it -- remains unclear.

Residents of the capital report disunion in the rebel ranks and instances of infighting between groups. Some of those fights appeared to be related to ideological splits, residents said, while others appeared to be battles over territory.

As in other parts of the country, Islamist rebel groups appear to be leading the fight in Damascus, including fighters from Jabhat al-Nusra, or the Nusra Front, a group that U.S. officials say has ties to Al-Qaida and that the United States said Monday it would designate a terrorist group.

Living conditions in the capital have deteriorated, with bread and heating oil in short supply. Residents reached by phone said electricity was available for only six to 12 hours a day, depending on the neighborhood. That's a marked difference from the beginning of the rebel offensive six months ago, when gasoline shortages were being felt but the capital otherwise was functioning.

In November, the greatest number of people killed in Syria died in and around Damascus -- at least the third month in a row that was the case, according to statistics compiled by Syrian human rights groups.