Book excerpt: TSA has the second-largest number of explosive detection canine teams in the Federal Government, after the Department of Defense. TSA's National Explosives Detection Canine Team Program has a critical mission to deter and to detect the introduction of explosives into all the Nation's transportation systems. With 985 teams today, including 675 teams handled by local law enforcement, and 310 teams handled by TSA inspectors, that is twice the number of teams that existed just 8 years ago. Most of us who have dogs know how incredibly intelligent and capable they are at detecting the slightest changes in their environments. When that intelligence is coupled with the highly selective breeding, months of intensive training, and breakthrough developments in science and technology, canines become one of the most trusted assets for law enforcement and military operations in critical environments. They serve as one of the most reliable security tools that exist today.