Teams of undercover police officers fan out across Los Angeles International Airport targeting what they call the "insider threat."
This potentially serious hazard isn't coming from travelers, but from those who work at the airport itself.
Law enforcement officials say airports around the country routinely monitor the thousands of employees, who must undergo a criminal background check and get fingerprinted. At LAX, the nation's second busiest airport, police screen employees and check IDs as part of a multi-agency operation.
CNBC was allowed exclusive access to a recent insider threat police operation as well as inside security operations at the airport, videotaping areas never before seen by the public.
"I think about everything. I think about the possibilities," said Los Angeles Airport Police Chief David Maggard Jr. "And then, what we try to do is get that information from the other people that have maybe had an experience with the tragic event or with the threat. And we try and gather that information and apply it here."