The British Armed Forces form the military of the United Kingdom, tasked with defence of the country, its overseas territories and the Crown dependencies; as well as promoting the UK’s wider interests, supporting international peacekeeping efforts, and providing humanitarian aid. They are: the Royal Navy, a blue-water navy with a fleet of 77 commissioned ships; the Royal Marines, a highly specialised amphibious light infantry force; the British Army, the UK’s principal land warfare branch; and the Royal Air Force, a technologically sophisticated air force with a diverse operational fleet consisting of both fixed-wing and rotary aircraft.
The commander-in-chief of the British Armed Forces is the British monarch, Queen Elizabeth II, to whom members of the forces swear allegiance. However the British parliament maintains the armed forces during times of peace with the passing of quinquennial armed forces acts. The armed forces are managed by the Defence Council of the Ministry of Defence, headed by the Secretary of State for Defence.
The UK is an active and regular participant in NATO and other coalition operations. The country is also party to the Five Power Defence Arrangements. Recent operations have included wars in Afghanistan and Iraq, the 2000 intervention in Sierra Leone, peacekeeping responsibilities in the Balkans and Cyprus, and participation in the UN-mandated no-fly zone over Libya. Overseas garrisons and facilities are maintained at Ascension Island, Bahrain, Belize, Bermuda, British Indian Ocean Territory, Brunei, Canada, Cyprus, the Falkland Islands, Germany, Gibraltar, Kenya, Montserrat, Nepal, Singapore and Qatar.
The United Kingdom tested its first nuclear weapon under Operation Hurricane in 1952, becoming the third nation in the world to achieve the status of a nuclear power. As of 2015, Britain remains one of five recognised nuclear powers, with a total of 225 nuclear warheads. Of those, no more than 160 are deployed and active. Its nuclear deterrence system is based on Trident missiles on board ballistic missile submarines.