Article snippet: With terrorist groups renewing calls for would-be attackers to target American rail lines, at least one local law enforcement agency in the U.S. is using drones to help guard against such a threat. The police chief for the Philadelphia-area's mass-transit system said he has known for some time that more than 140,000 miles of rail lines crisscrossing America are "porous" and had thought for a while of using drones to monitor the agency's tracks. He initiated the drone program after an article in the latest issue of Transportation Security Administration to send a security notice to law enforcement across the nation, ABC News has learned. Amid this threat, Thomas Nestel, police chief for the Southeastern Pennsylvania Transit Authority, told ABC News' David Kerley, that drones are "a great way for us to patrol a track without walking on the track, putting officers in jeopardy safety-wise." "Using the drone can cover a whole lot of area in a much faster span of time," he said. "This was bouncing around in my head for a little while and then when that ... article came out, I pulled the trigger, I said, 'Let's do it,'" Nestel said. The transit-agency's drone, which is equipped with a high-resolution camera, can help officers detect intruders or anomalies on the tracks and provide information that could lead authorities to stop trains before they reach a problem area. John Cohen, a former counterterrorism coordinator for the Department of outlined a potent... Link to the full article to read more