A virus has been detected on the control systems for the US army’s unmanned military drones, according to a report by Wired‘s Danger Room blog.

The keylogger virus, which keeps a record of all the keystrokes on a host machine, was discoverd two weeks ago on the ground control stations for unmanned arial vehicles (UAVs) at the Creech Air Force Base in Nevada.

According to Danger Room’s sources, it was removed several times but kept returning. Eventually, the ground control stations were wiped and rebuilt.

It is not known whether the ground control stations were specifically targeted or if the infection was accidental. There is no direct evidence that any data was leaked,

Danger Room reports that while the use of external USB drives is banned in most US military networks, this was not the case at the Creech Air Force Base until this virus was detected.

According to cybersecurity analyst and author Jeffrey Carr, it is "theoretically possible" that the virus could have spread to the control systems of other air forces using the base via the Global Information Grid, the US Department of Defense’s universal network.

"This could include Britain’s Royal Air Force whose 39 Squadron use Creech AFB as ground control for their own fleet of UAVs," Carr wrote on his blog today.

The incident is the second serious security relating to unmanned military drones. In 2009, the Wall Street Journal reported that video feeds transmitted by drones in Afghanistan had been intercepted by "militant groups trained and funded by Iran". It later emerged that those video feeds were not encrypted.