An elite component of the Royal Marines is responsible for guarding British nuclear weapons and ballistic missile submarines. Known as the Commachio Group, the unit was first formally activated in May 1980. The key naval installation they guard is the Royal Naval Armament Depot (RNAD) Coulport in Scotland, where British ballistic missile submarine (SSBN) missiles and warheads are stored. Commachio commandos escort the submarine out to open waters, ostensibly to protect it from terrorist attacks and anti-nuclear demonstrators.
The unit is named after Lake Commachio, north of Ravenna, Italy, where Royal Marine Tom Hunter won the Victoria Cross in World War II. Commachios were selected from Royal Marine commando units and the number eventually grew to number 350. Other missions that they have responsibility for include anti-smuggling operations and protection of U.K. oil rigs in the North Sea.
Commachio group, now reorganized into the Fleet Protection Group, and are primarily responsible for the security of British Nuclear Deterrent, in the form of Trident submarines. For a period they were also responsbile for maritime counter-terrorism, a task now covered by the Special Boat Service.