The Specialist Firearms Command is the firearms unit of the Metropolitan Police. The Command is responsible for providing a firearms-response capability, assisting the rest of the service which is not routinely armed.

A firearms unit is an armed unit within each territorial police force in the United Kingdom. For the most part, the police forces of the United Kingdom are unarmed; however, all have firearms units to provide the police force with the capability to deal with armed criminals. A police officer cannot apply to join the firearms unit without first finishing their two-year probationary period, with a further two years in a core policing role for some forces. Firearms unit is the most common name outside of the capital, while that of London's Metropolitan Police Service is called the Specialist Firearms Command, Trojan, or SCO19. Within the media, it is sometimes compared to the SWAT units of the United States.