The Air Force has ordered 40 more MQ-9 Reaper unmanned aircraft from maker General Atomics Aeronautical Systems under a contract worth more than $319 million, the Pentagon said recently.

The sole-source contract includes 40 containers for the Block 1 hunter-killer drones also capable of conducting high-altitude surveillance.

The contract is headed by the Air Force’s Aeronautical Systems Command in Wright Patterson AFB, Ohio. General Atomics is expected to complete delivery by September 2013.