Reconnaissance plays a key role in military planning -- drones help military commanders keep track of their own troops and also spot enemy troops that might be waiting to ambush U.S. soldiers.
Flying robots like the Predator provide constant real-time data on troop movements, enemy locations and weather. In at least one case, a flying robot did a lot more than just spot the enemy: Predators can be fitted with Hellfire missiles, and when one of these Air Force drones spotted an anti-aircraft gun in southern Iraq in March 2003, it used one of the Hellfires to take it out [ref].
To learn much more about the Predator, see How the Predator UAV Works.
Today's military robots are limited in their autonomy and their range. They are essentially tethered to human controllers. The Defense Advanced Research Projects Agency (DARPA), the U.S. government entity that funds and develops new technologies for military use, recently held a widely publicized robot race to see how far along robot AI had come. It turns out that AI is still pretty limited -- not a single robot completed the course. So even as the abilities of robots increase, it seems that for the foreseeable future, a human soldier will still be required at the control unit.
For more information on military robots, check out the links on the following page.