How did Sunni insurgents gain momentum in Iraq?

Known as ISIS or ISIL, a Sunni militant group has taken over parts of the northern city of Mosul, a strategic hub for Iraq’s oil industry, as well as a gateway to Syria. Judy Woodruff is joined by Laith Kubba of the National Endowment for Democracy and Kimberly Kagan of the Institute for the Study of War to discuss the larger impact of the takeover on Iraq and its neighbors.