The New York Times reports: For months, the patchwork of rebel brigades spread across northern Syria watched with foreboding as a new group gradually expanded its control, filling a vacuum left by nearly three years of war.

The group, the Islamic State of Iraq and Syria, which is linked to Al Qaeda and known as ISIS, seemed less interested in fighting President Bashar al-Assad than in imposing its ultraconservative version of Islam, antigovernment activists said. It banned smoking, ousted other rebels from their bases, and detained and executed those it decided were opposed to its international jihadist project.

Last week, mounting tensions between the Islamic State of Iraq and Syria and other rebel groups exploded into clashes that have raged across northern Syria, left hundreds dead and further shattered the battle lines in a conflict that is increasingly destabilizing neighboring countries. Rebel fighters have driven the group from a number of areas in recent days, and on Wednesday they ejected it from its headquarters in the major city of Aleppo, dealing the group a sharp reversal. [Continue reading…]