It is impossible to confirm at present whether the ISIS claim on Twitter to have executed 1,700 Shia soldiers in Iraq is accurate, or an exaggeration intended to create fear among the Shia populace. But earlier, the UN high commissioner for human rights, Navi Pillay, expressed “extreme alarm” at the situation and spoke of verified reports of “summary executions and extrajudicial killings”. Some of the reports cited suggest that Iraqi security forces are being purged, though it is unclear whether there is an ethnic dimension to all of the killings.