The US since last year has been secretly flying unmanned surveillance aircraft in small numbers over Iraq to collect intelligence on insurgents, according to US officials.

The program was limited in size and proved little use to US and Iraqi officials when Islamist fighters moved swiftly this week to seize two major Iraqi cities, the officials said.

Before the Islamist offensive, the program was expanded based on growing US and Iraqi concerns about the expanded military activities of al Qaeda-linked fighters. […]