Washington, Jun 24 (IANS): Ten US Air Force planes, including two E-4B "doomsday" aircraft, were damaged when a tornado hit the Offutt Air Force Base in Nebraska, the media reported.

Nicknamed the Air Force's "doomsday" plane, the Boeing-made E-4B serves as an aerial command centre in case of national emergency or destruction of ground bases, an Air Force officer told CNN on Friday.

It provides a "highly survivable command, control and communications centre to direct US forces, execute emergency war orders and coordinate actions by civil authorities", according to the Air Force.

"The E-4B serves as the National Airborne Operations Centre and is a key component of the National Military Command System for the President, the Secretary of Defence and the Joint Chiefs of Staff," Air Force spokesperson Col. Patrick Ryder told CNN.

The aircraft is also protected against the effects of electromagnetic pulse and has an electrical system designed to support advanced electronics and a wide variety of communications equipment, according to the Air Force's fact sheet.

The Air Force has four E-4Bs in active service, and the primary aircraft was off-station during the tornado on June 16, according to Ryder.

"There is no impact to the E-4B's primary mission, so it remains capable of completing its National Airborne Operations Centre," he said.

In addition to the two E-4B planes, eight RC-135 reconnaissance aircraft were also damaged in the storm that took out some trees and damaged buildings on the base.

Six of these eight aircraft have now been returned to mission-capable status, Ryder added.