The armed forces of the United Kingdom, commonly known as the British Armed Forces or Her Majesty's Armed Forces, and sometimes legally the Armed Forces of the Crown, encompasses a navy, an army, and an air force. With a reported personnel strength of 429,500 in 2006 (195,900 regular force, 191,300 regular reserve, and 42,300 volunteer reserve), the British Armed Forces constitutes one of the largest militaries in Europe, though only the 26th largest in the world by number of troops. blank">Strength of UK Regular Forces by Service and whether trained or untrained at 1 April each year, dasa.mod.uk The British Armed Forces however have the third highest expenditure (only behind the _U.S. and France) of any military in the world. Their Commander-in-Chief is the British monarch, HM Queen Elizabeth II and they are managed by the Defence Council of the Ministry of Defence. Consistent with longstanding constitutional convention, however, the Prime Minister holds de facto authority over the armed forces.

The British Armed Forces are charged with protecting the United Kingdom and its overseas territories, promoting Britain's wider security interests, and supporting international peacekeeping efforts. They are active and regular participants in NATO and other coalition operations.

Recent operations have included wars in Afghanistan and Iraq (2001 and 2003 respectively), intervention in Sierra Leone (2000), and ongoing peacekeeping responsibilities in the Balkans and Cyprus. Overseas garrisons and facilities are maintained at Ascension Island, Belize, Brunei, Canada, Diego Garcia, the Falkland Islands, Germany, Gibraltar, Kenya, and the Sovereign Base Areas (Cyprus). House of Commons Hansard, publications.parliament.uk