Fighting kidnapping and terrorism are part of their duties, as well as protection and evacuation of U.S. citizens out of crisis areas and training of personnel in foreign countries.

The team's three primary missions are:[5][3] MSD cooperates closely with other federal agencies, such as the Secret Service, the Fleet Antiterrorism Security Teams of the United States Marine Corps, the Federal Bureau of Investigation and local law enforcement agencies, both domestic and foreign.

MSD agents use advanced combat helmets, ballistic protective glasses such as Oakleys, body armor, gas masks, radio transceivers with headphones, tactical first aid kits, ballistic vests, various hydration systems, current-generation night vision goggles and GPS handheld devices such as Garmin 60cx, and other geolocation equipment.

MSD agents are also trained to use less-than-lethal weaponry include OC, or pepper spray, extendable batons and stun grenades.

Diplomatic Security MSD agents were involved in Bosnia and Liberia[6] protecting U.S. diplomatic missions and arresting terrorists, as well as the investigation of terrorists bombings in a United States Army barracks in Dhahran, Saudi Arabia in 1996 and the 1998 United States embassy bombings in Tanzania and Kenya.

More recent missions have included operations in Iraq, Afghanistan, Haiti, Pakistan, Jamaica, and in various other countries conducting MTTs such as Mexico.