The
ballistic missile submarineHMS Vanguard, lead ship of
her class, arrives at
HMNB Clyde in
Faslane, Scotland, following a patrol in 2010. Ballistic missile submarines like Vanguard were introduced during the
Cold War, and serve as the third leg of the
nuclear triad in countries which also operate nuclear-armed land-based missiles and aircraft. Their intended role in the nuclear triad is to provide a
second-strike capability in a defensive capacity, or to offer nuclear-armed nations a
first-strike weapons platform. In addition to the first- and second-strike capabilities, Vanguard carries a
handwritten letter from the
Prime Minister of the United Kingdom which contains orders on what action to take in the event that an enemy nuclear strike has destroyed the
British government.Photograph: Tam McDonald