Confronting the threat posed by mystery drone swarms over the U.S.

60 Minutes has been looking into a series of eerily similar incidents going back years.

In each, drones first appeared over restricted military or civilian sites, coming and going often literally "under the radar" The wake-up call came just over a year ago when drones invaded the skies above Langley Air Force base in Virginia .

NORAD 's radar systems designed during the Cold War to detect high-altitude air, space or missile attacks were unable to detect low flying drones that could be seen with the naked eye.

Defense news site documents dozens of drone intrusions at sensitive infrastructure and military installations.

Drones that can spy can also destroy.

In overseas war zones, the U.S. military has broad authority to bring down menacing drones with gunfire, missiles, and electronic jamming.

Some F-22s stationed at Langley were moved to nearby air base for their own protection.

NORTHCOM is developing fly-away kits with the latest anti-drone technology to be delivered to bases besieged by drones.

Gen. Gregory Guillot was given the authority to cut through the red tape and coordinate counter drone efforts across multiple government agencies.

He says new, more sensitive radar systems are being installed at strategic bases.