Are member states really failing to pay their dues?

Nato members agreed to pay 2 per cent of their gross domestic product (GDP) towards the alliance’s defence budget at a meeting in Newport, Wales, in September 2014, pledging to reach that target by 2024.

President Trump first raised doubts about their commitment to this goal in an interview with The New York Times in March 2016, during the presidential election campaign.

He repeated the charge at the opening of the organisation’s new headquarters in Brussels on 25 May last year: “I have been very, very direct with Secretary Stoltenberg and members of the alliance in saying Nato members must finally contribute their fair share and meet their financial obligations.

“But 23 of the 28 member nations are still not paying what they should be paying and what they are supposed to be paying for their defence.”

“This is not fair to the people and taxpayers of the United States and many of these nations owe massive amounts of money from past years. And not paying in those past years.”

Again this morning, he attacked those not paying their dues as “delinquent”.

And the president appears to have a point. By 2017, only the US, UK, Greece, Poland and Estonia had met the pledge.

Mr Trump’s annoyance with Germany in particular, whose GDP is the biggest among members other than the US, seems justified, given that the US accounted for 71.1 per cent of Nato’s total defence expenditure last year, adding $686bn (£518bn) to the war chest. That’s 3.57 per cent of its GDP.

The UK, which contributed £42bn compared to Germany’s £34bn, appears to share his view, with former defence secretary Michael Fallon telling CNBC this week: “Half the alliance - 16 of the 29 countries - don’t even spend 1.5 per cent, let alone the 2 per cent that we all agreed on four years ago in Wales”.

“Four years on, and not enough European countries are making progress towards it and they need to do that and the president’s criticisms are quite valid.”