The U.N. on Wednesday called its highest level of emergency for the humanitarian crisis in Iraq, where hundreds of thousands have been driven from their homes and tens of thousands have been trapped in a desert mountain by the advance of Islamic militants across the north of the country. The declaration of a "Level 3 Emergency" will trigger additional goods, funds and assets to respond to the needs of those displaced, said U.N. special representative Nickolay Mladenov, who pointed to the "scale and complexity of the current humanitarian catastrophe."