Over £2 billion has already been spent on a replacement for the UK's nuclear weapons programme, even though the government has yet to officially commit to replacing it.
Exactly £2,068 million was spent on the replacement for Trident up to the end of March this year, the government confirmed.
Trident is the UK's ageing Scotland-based nuclear weapons programme, which has long been controversial due to the Scottish parliament's opposition to nuclear weapons.
The decision on whether to commit to a full replacement system was deferred by the government until after the 2015 general election due to a disagreement between the two coalition parties on how to proceed.
However, items such as a "weapons handling and launch system" and "gearbox components" have already been purchased, and the design for the submarines "will be finalised" in 2019, according to Conservative peer Lord Astor of Hever.
In 2012, deputy prime minister Nick Clegg said: "The coalition agreement is crystal clear. The final decision on the replacement of Trident will not be taken until 2016, however much other people may not like it."
The Conservatives want a like-for-like replacement of the Trident submarines, while the Liberal Democrats want to downscale the system. Some other parties, such as the Scottish National Party, want to get rid of the UK's nuclear weapons altogether.