For at least three decades, experts have noted the growing militarization of America’s police forces. The proliferation of Special Weapons and Tactics forces, or SWAT forces, is the most obvious example of that trend. Originally, such units were designed to deal with exceptionally dangerous situations (such as mass hostage incidents) in which lightly armed police would be outgunned. Not surprisingly, the first SWAT contingents originated in America’s largest and most dangerous cities.
Source