A computer virus has infected the cockpits of America’s Predator and Reaper drones, logging pilots’ every keystroke as they remotely fly missions over Afghanistan and other war zones.

The virus, first detected nearly two weeks ago by the military’s Host-Based Security System, has not prevented pilots at Creech Air Force Base in Nevada from flying their missions overseas. Nor have there been any confirmed incidents of classified information being lost or sent to an outside source. But the virus has resisted multiple efforts to remove it from Creech’s computers, network security specialists say. And the infection underscores the ongoing security risks in what has become the US military’s most important weapons system.

Military network security specialists aren’t sure whether the virus and its so-called “keylogger” payload were introduced intentionally or by accident; it may be a common piece of malware that just happened to make its way into these sensitive networks. The specialists don’t know exactly how far the virus has spread. But they’re sure that the infection has hit both classified and unclassified machines at Creech. That raises the possibility, at least, that secret data may have been captured by the keylogger, and then transmitted over the public Internet to someone outside the military chain of command.

Drones have become America’s tool of choice in both its conventional and shadow wars, allowing US forces to attack targets and spy on its foes without risking American lives. Since President Obama assumed office, a fleet of approximately 30 CIAdirected drones have hit targets in Pakistan more than 230 times; all told, these drones have killed more than 2,000 suspected militants and civilians, according to the Washington Post.

More than 150 additional Predator and Reaper drones, under US Air Force control, watch over the fighting in Afghanistan and Iraq. American military drones struck 92 times in Libya between mid-April and late August. And late last month, an American drone killed top terrorist Anwar al-Awlaki — part of an escalating unmanned air assault in the Horn of Africa and southern Arabian peninsula.

But despite their widespread use, the drone systems are known to have security flaws. Many Reapers and Predators don’t encrypt the video they transmit to American troops on the ground. In the summer of 2009, US forces discovered “days and days and hours and hours” of the drone footage on the laptops of Iraqi insurgents. A $26 piece of software allowed the militants to capture the video.