The day after Memorial day in the US is not a bad one to ask how much money the country spends on national defence. It is a simple enough question and, given the state of public finances, certainly an important one. But bureaucratic obfuscation, impenetrable accounting and a dose of serial denial make getting an answer difficult.

The number the Pentagon prefers to advertise is the base budget, which funds salaries, maintenance and equipment purchases. Officials also divulge the costs of waging continuing wars. For the 2012 fiscal year the US has set aside $531bn for the base budget and $115bn for overseas contingency operations. But as Winslow Wheeler, a defence analyst, points out, to protect its citizens the US spends a lot more than that. Dig through the budget and you will find spending by the departments of energy, state and others to pay for border security, to support allies, to assist veterans and to maintain the nuclear arsenal.

After adjusting for double counting and offsetting receipts, in 2012 the US will spend: $125bn on veterans, $49bn for separate retirement funds and sundry activities, $42bn on homeland security, $22bn for foreign military sales and aid, and $18bn broadly on nuclear programmes. Throw in $58bn to cover a fair share of the government’s interest costs and the total hits $960bn. The consequences are profound. US spending on national defence jumps from about 3 per cent to 6 per cent of forecast GDP and rises from about 14 per cent to about 26 per cent of total federal spending.