SWAT was a special law enforcement unit in the United States.
In the Oval Office in 1969, the Eleventh Doctor asked for a SWAT team to be mobilised, among other requests, while attempting to work out more about a mystery caller contacting President Nixon. When the situation became an emergency, the Doctor noted that there was no longer time to call a SWAT team, and decided to deal with the matter himself, accompanied in the TARDIS by his companions and Canton Delaware. (TV: The Impossible Astronaut)
In 2011, during the Miracle, a SWAT team, accompanied by Andy Davidson, was sent to Mary and Geraint Cooper's house to rescue Gwen Cooper's family, who were being held hostage by agents of the Three Families. On orders from their leader, a SWAT agent and fellow agent Johnson, both heavily armed, entered the house, shot one man, and then spread out across the home to search the place for more hostiles. (TV: Immortal Sins)