The cost of the war in Afghanistan to the British taxpayer has reached £17.4 billion (nearly $33.9 billion) the Government disclosed yesterday, as it set out details of the accelerated exit plan for its troops.
The UK presence will be reduced from 9000 to 5200 by the end of next year, and all but a few hundred of the remaining troops will return home during 2014.
Ministers are hastening Britain's exit from the 11-year war despite fears that Afghan forces could lose control of parts of the country after Western forces leave.
Chancellor of the Exchequer George Osborne is believed to be among senior Cabinet ministers pressing for more drastic and more immediate cuts in troop numbers, not least because of the huge sums involved in maintaining the military operation.
Defence Secretary Philip Hammond told MPs in Parliament that the war had cost £17.4 billion in addition to his department's core budget. His disclosure indicates that the final price tag is likely to be around £20 billion.
Although the number of troops in Afghanistan will be significantly smaller in 12 months, the Government's decision is still viewed by military commanders as a far better outcome than they had expected.
The head of Britain's armed forces, General Sir David Richards, persuaded Prime Minister David Cameron that at least 9000 troops should be kept until the end of next year's fighting season in the northern summer.
Failure to do so would jeopardise hard-won gains and put undue strain on Afghan security forces, he warned.
But the withdrawal will begin in April, with fewer replacements sent over in the regular six-monthly rotation of troops.
Another reduction will take place in September or October.
The military faces another round of decisions on the pace of the withdrawal in 2014, as well as on how many military advisers to leave behind to support Afghan forces.
A few hundred other troops will remain to organise the return of expensive military hardware, including tanks and helicopters, to Britain.
The plans will be largely influenced by actions taken by the United States. It is believed that the US could have as few as 6000 personnel in the country after 2014.