The edict from the group emerged as its fighters retreated in response to an ultimatum from rival Islamist groups to leave the Syrian battlefield. One source of tension is its attempt to establish an Islamic caliphate, centred on Raqqa, where it has imposed harsh sanctions on anyone falling foul of its restrictive version of Islamic law. In a statement posted on jihadist websites, the group’s leader ordered Christians in the city to pay a tax in gold if they wished to continue living under the group’s ‘protection’.