A coalition of Syrian rebel groups is escalating an offensive against forces loyal to the Syrian government in the strategic city of Aleppo, rebel sources said, Al Jazeera reported Aug. 2. Government forces and their allies recently cut off the main supply lines to rebel-held areas in the city, ostensibly beginning a siege that endangers the lives of the hundreds of thousands of people who live there. The city, a commercial and cultural hub before the war began more than five years ago, has long been prized by all sides in the conflict. Were they to force rebel fighters from Aleppo city, pro-government troops would deal a substantial blow to the rebel cause in the war. Now, with fighting intensifying around the city, high numbers of civilian casualties seem increasingly likely. At least 30 civilians have reportedly died in government-held parts of the city in the past few days, while airstrikes by the Syrian government and Russia pounded the city and surrounding countryside on Aug. 2, according to the Syrian Observatory for Human Rights. In eastern parts of the city, civilians burned tires in an attempt to obscure targets from airstrikes.