A few years ago, when satellites were promoted as the only means of aeronautical navigation from take-off to landing, former FAA Director Langhorne Bond painted a dark winter night with weather below the limit. In this case, he said, terrorist gps jammer could become "weapons of mass destruction." The FAA downplayed baseless speculation. But in a recent report on GPS-dependent ADS-B, Inspector General DOT took the issue more seriously and asked the FAA "to work with the US intelligence community to assess this potential threat."
GPS signal blockers can saturate relatively weak GPS signals. The Pentagon recognized early on that its navigation and guidance systems could be plagued by interference, and tried to install weapons and vehicles with backup guidance systems-or to ensure that troops could use outdated maps and compass GPS locked.
The South Korean government reports that North Korea has imported "about 20 radar and signal jammers" from the former Soviet Union. These on-board units have been deployed near the border and interfere with GPS signals within a range of 50 to 100 kilometers. The most likely use is for law enforcement to prevent illegal (but not malicious) use of drones.