In the past, what Europe spent on defence mattered less, not least because the US had the means to carry the load. However, the US is simply not the power it once was. When NATO was formed in 1949, the US accounted for almost half of global output. In 1989, when the Berlin Wall fell, it still accounted for around a third. Today it accounts for approximately one quarter, and it may account for as little as one sixth by 2030. All of this as China grows stronger by the year.

For the UK, this debate matters also, for two reasons. First, in a letter to Gavin Williamson, the US Defence Secretary outlined his expectation for the British to spend more than 2 per cent of GDP on defence, not least because the UK is more than just a European power. It was inferred by the British that the “special relationship” might suffer if the UK failed to spend more on defence.

Second, the UK – like the US – suffers when Europeans fail to invest sufficiently in defence. This is not so much because of the lacking assets, but because European countries invest money they should have spent on defence into domestic programmes, giving them, potentially, an unfair economic advantage over the UK and US.