K-9 explosive detection teams are a psychological and physical deterrent to potential threats from those who seek to deploy explosives. These teams are part of a collaborative inter-agency initiative that includes the Transportation Security Administration, federal and state Departments of Homeland Security, and state and local law enforcement agencies. Amtrak explosives detection teams are divided between standard explosives detection and vapor wake detection. Vapor wake detection dogs are trained to alert on a passing individual. Amtrak currently has the most K-9 units in the railroad industry with vapor wake capabilities. Additionally, The APD currently has two working narcotics detection K-9 teams.