As the engines of Russian bombers rumble above the English channel, the government could be about to freeze defence spending.
Sources inside the treasury told The Times the move, said to be possible after the election, has stirred the Tory ranks and spawned whispers of a rebellion.
The UK currently spends 2.07 per cent of its annual GDP on defence, just above the Nato target of two per cent. That's more than Germany (1.14 per cent) and France (1.5 per cent), but Angela Merkel’s nation has a limit on its military movements. The US spends far more, 3.6 per cent, while in 2013, according to the World Bank, Russia spent 4.2 per cent.
Below is a map showing how much different countries spent on defence in 2013, as a percentage of GDP. If no figure was available for 2013 (the most recent year) then the next available figure was used, but dating no further back than 2010.
But for Nato members, there's hope: Russia may have to cut its defence budget as sanctions bite and the rouble weakens, China, although it spends the second most in the world in raw cash, is expanding its military spending at just above the rate its economy is expanding. What is more, if the UK does cut defence spending, it won't be the only Nato country to have fallen below the two per cent target (see graph).
The counter argument is that we rely too heavily on the US for our military might. Vladimir Putin is a leader as unpredictable as he is bellicose, while the fight against terrorist groups and IS in particular looks like dragging on into the long term. The Ukrainian conflict is of greater concern. Big countries aren't used to going to war any more, so when Russia raises the stakes there is reluctance to put Nato lives at risk. Yet there are suggestions a full-blown proxy war could erupt in Ukraine. Much of what keeps violent genies in bottles, the argument goes, is the threat of retaliation, so we should keep that capability.
Some of the data in the graph is more recent than the mapped figures, and may not match.
Of course, although its important to look at what percenatge of its income a country spends in defence, the total amounts matter, too.
The above graph illustrates just how huge the US's budget is. Along the bottom is total spending, while the left axis shows spending as a percentage of GDP. Red bubbles mean a country increased its GDP proportionate spending between 2012 and 2013, the most recent year for which there is full data. Transparent bubbles are non-Nato members, and the size of the bubbles is a second way of visualising the total 2013 dollars spent. Not best graphing practice, but it helps make it clearer. All data is from the Stockholm International Peace Research Institute.