The Pentagon worries about quadcopters

http://www.chicagotribune.com/news/sns-wp-blm-pentagon-drones-ad0a4d1c-6929-11e6-91cb-ecb5418830e9-20160823-story.html

"The U.S. military has begun studying small drones and how best to respond. Earlier this month, the Defense Advanced Research Projects Agency (DARPA) issued a request for ideas on how to protect troops from the new threat; it is planning a workshop next month. 'We're looking for scalable, modular, and affordable approaches that could be fielded within the next three to four years and could rapidly evolve with threat and tactical advancements,' a DARPA program manager, Jean-Charles Ledé, said in a statement.
Closer to the battlefield, the Marine Corps has begun integrating small drones into training exercises at the Air Ground Combat Center in Twentynine Palms, Calif., Neller said. A Marine or soldier who spots a drone overhead would typically shoot it down, but smaller drones can operate surreptitiously and elude radar since they are barely larger than a bird. Their small motors make acoustic detection enormously hard, and while wide-area camera sensors deployed on the ground might detect a drone, they usually require large computational resources in the field. One solution is an electronic signal jammer to prevent a drone's operator from flying within a certain vicinity, an approach that U.S. forces have studied."

You build something useful and beneficial, then the bad guys get hold of it... every time.