The Counter Assault Teams (CAT), Counter Sniper Teams (CS), and Emergency Response Teams (ERT) are all highly trained tactical units of the U.S. Secret Service. They operate domestically and internationally to provide inner, middle and outer perimeter tactical support, and long range response for the President, Vice President, visiting heads of state, National Special Security Events and other protective security operations of national significance. The U.S. Secret Service Special Operators Association, Inc. is a 501(c)(4) non-profit corporation, separate from any U.S. Government agency.