Since the beginning of the revolt against Syrian President Bashar al-Assad, the northern city of Aleppo has been the uprising's biggest question mark. Syria's largest city was a hotbed of resistance to the Assad regime during the 1980s, but -- apart from scattered protests of university students -- had largely stayed silent during the current 16-month uprising. Aleppo's failure to rebel spurred jokes, and no small amount of frustration, from Syrian activists: One famous protest sign lamented that the city "wouldn't rise even if it took Viagra."
Nobody is making jokes any more. Shortly after a brazen bombing in Damascus killed four top Syrian security officials, violent clashes broke out for the first time in Aleppo. As rebel forces made headway in wresting several neighborhoods from government control, the city braced for Assad's retaliation. The BBC reported that Syrian fighter jets were used to attack rebel positions there, while the Associated Press confirmed that the jets flew over the city but did not report the attack.
But so far, the Syrian military -- challenged on multiple fronts by the rebels in recent days -- has not been able to oust the rebels from their toeholds in Aleppo. Here, rebel fighters rest at a primary school in the center of the city.