"In a new report called “Limiting Armed Drone Proliferation,” published by the Council on Foreign Relations, Micah Zenko and Sarah Kreps argue that the time has arrived for the U.S. to set regulatory limits on the use of drones. Because drones do not have pilots, they write, the threshold for launching war is lower -- and the planes cannot avoid sudden danger as easily. Countries may also fire on manned fighter planes -- confusing them with drones."