Just when you think the instability in the Middle East can't get any worse, it does. The Sunni extremist takeover of much of northern and western Iraq threatens to create a zone of chaos and violence that respects no national borders. In Riyadh, Tehran and Washington key strategic players have a huge stake in what happens next. HARDtalk speaks to Zuhair al-Naher, a spokesman for the Dawa party of Iraq's Prime Minister, Nouri al-Maliki, and to former US ambassador in Baghdad, Christopher Hill. Can Iraq be brought back from the brink? Show less