That’s what Slate just asked me, P.W. Singer and John Pike from Globalsecurity.org. The answer is yes, probably. From Slate:
As reporter David Axe discussed in his book War Bots: How U.S. Military Robots Are Transforming War in Iraq, Afghanistan, and the Future, the Pentagon was able to destroy its first generation of unmanned spy planes by remote control, in case they fell into enemy hands. And the feature really worked: Axe reports that pilots accidentally blew up a Northrop Grumman Global Hawk prototype during a 1999 test. The RQ-170 that went down in Iran last week probably had a self-destruct mechanism as well. The technology isn’t foolproof, though. If the plane lost contact with the ground, the self-destruct button wouldn’t work. Even when onboard explosives detonate, they don’t always completely destroy the vehicle. When drones have gone down in the past, the military has sent in manned attack jets to finish the job.