MINNEAPOLIS — Minnesota’s largest airport has had 10 breaches of perimeter security fences and gates in the past decade, several involving military service members who strayed into restricted areas, according to an Associated Press investigation.

The breaches are among at least 268 the AP documented at 31 major U.S. airports from January 2004 through January 2015. Those incidents ranged from fence jumpers taking shortcuts and intoxicated drivers crashing through barriers to mentally ill intruders looking to hop flights. None was terrorism-related.

Airports said breaches are relatively rare. Security measures typically include fences, cameras and patrols, but there are gaps. Not all of the miles of fences are routinely patrolled or covered by surveillance cameras — as was the case at Minneapolis-St. Paul International in 2012, when an Army reservist walked into a restricted area on his way back to barracks while the video surveillance system was down.

Police records show another incident in 2012, when an Air Force reservist walked onto a runway that had been shut down for snow removal. Other incidents were in 2009, 2008, 2007, 2005 and 2004.

Because commercial airlines share the airfield with National Guard and reserve units, there are more opportunities for service members to go astray, airport spokesman Pat Hogan said. Airport officials try to ensure that military officials explain to troops what is off limits, Hogan added.

Airport workers are trained to question anyone without a badge in a secure area, and in recent years the airport has offered a $20 reward for anyone who issues such a challenge.