The group last week murdered Khaled al-Asaad, 82, the keeper of the historic city of Palmyra. Its latest destruction raises the question of what will become of the ancient oasis city, one of the best-preserved classical sites, in a region beset by civil wars and conflict.
After sweeping through much of northern Iraq last year, Isis set its sights on the ruins near its stronghold of Mosul, ransacking museums, the ruins of once-mighty cities such as Nimrud and Hatra, and desecrating historic Christian and Shia shrines.