The Syrian army is battling the self-proclaimed Islamic State of Iraq and al-Sham (ISIS) militants just 1-2 km (one mile) from the ancient city of Tadmur, home to a UNESCO World Heritage site, the Syrian antiquities chief told Reuters on ThursdayMaamoun Abdulkarim said that if the group seizes the city, which is also known as Palmyra: "They will destroy everything that exists there."