As he arrived in Brussels for a meeting with European defence chiefs, General James Mattis had warm words for Nato, describing it as the “fundamental bedrock” of the US’s relationship with Europe. After months of Nato-bashing by Donald Trump, it will reassure America’s allies to know that the President’s defence secretary takes a rather more positive view.

Nevertheless, it is unlikely that General Mattis will take a more conciliatory position than his boss when it comes to the question of Nato’s funding. After all, America’s concern that other members of the alliance do not pay their fair share of Nato’s costs is not an invention of the new regime. The Obama administration made it clear on several occasions that it was uneasy at the defence cuts being made by its European partners; and anxiety at the prospect of further retrenchment in the UK was particularly troubling. As things stand, Nato says that only the US, the UK, Poland, Estonia and Greece are meeting the target of spending at least 2 per cent of GDP on defence.

Even this is the subject of dispute. A report by the International Institute for Strategic Studies concluded on Tuesday that Britain’s defence spending had dipped just below the 2 per cent figure. Unsurprisingly the Ministry of Defence said the calculation was flawed. Either way though, the US wants its allies to stump up more. The Prime Minister appeared to win a commitment to Nato’s future from President Trump when she visited Washington but America wants firm financial assurances in return.

In truth, the Americans are right to press for greater input from their partners. Austerity may still be stunting growth across Europe and the last thing the world needs is a new arms race; but now is not the moment to let Nato wither. General Mattis described it yesterday as “the most successful military alliance in history” and it is important for European and global security that it remains so.

Earlier this week the New York Times reported claims by unnamed intelligence source that Russia has deployed a new cruise missile in breach of the 1987 Intermediate-Range Nuclear Forces Treaty. The reports were conveniently timed for the Nato summit, and were immediately met with a firm denial from the Kremlin. Yet at their heart is the indisputable truth that Russian intentions towards the West are more uncertain today than at any time since the collapse of the Soviet Union. Nato is the only effective bulwark against the potential strategic threats posed by Moscow.