"Operation Foul Ball."
It sounds like something from a Hollywood action thriller, but it was in fact the name of a secret security program at last year's MLB All-Star Game in Minneapolis.
The New York Times revealed the Department of Homeland Security experts used last year's baseball showcase at Target Field as a test case for a radar system to detect drones flying above the 40,000-seat stadium.
Security experts see privately operated drones as a growing threat to public safety, but the newspaper said that in spite of the use of the expensive, advanced detection system, they actually had no way of stopping drones from flying into the stadium on that day.
It also struggled to identify who was operating the machines, and given the expense of the program, baseball officials decided against using the technology in post-season games.
More than 120,000 people filled Target Field over the three days of events that ran during the All-Star break last July.
According to MPR, the Federal Aviation Administration started including "quadcopter" drones in its flight restrictions at sporting events where the capacity is more than 30,000.
This stops aircraft from flying lower than 3,000 feet within 3 miles of stadiums from an hour before a game to an hour after, but MPR notes many drone operators ignore the rules, and some are not even aware such a rule exists.