Riot police and army personnel take up positions during clashes with members of the Muslim Brotherhood and supporters of ousted Egyptian President Mohamed Mursi around the area of Rabaa Adawiya square, where they are camping, in Cairo . Photograph: Asmaa Waguih/Reuters

The violent crackdown on sit-ins in Cairo became inevitable when the Muslim Brotherhood replied to an invitation for dialogue from sheikh al-Azhar Ahm(...)