Britain’s Syrian Observatory for Human Rights said that after intensive clashes with government troops, Islamic State forces captured Mahin. What started out as protests against the government of President Bashar Assad in 2011 has turned into a civil war that has also attracted militants from around the world, fanned by rising sectarianism in the region. In a chilling reflection of this increasingly entrenched reality, rebels in Douma, a suburb of the Syrian capital that came under heavy bombing, have paraded government loyalists in cages in the streets, using them as human shields against further attacks.