It has been clear since the presidency of Barack Obama that Europe can no longer rely on US military protection. Even Nato members, able to invoke Article 5 of the treaty whereby an attack on one is an attack on all, cannot be certain how committed America would be to their defence.

The Americans are determined that European countries should spend more on their own security and not just assume that Uncle Sam will come to the rescue. Until now it has been a theoretical argument. With Russian troops poised to invade Ukraine, it has become very real indeed.

Vladimir Putin is testing out many things about Western attitudes, and one is the extent to which European countries are prepared to defend themselves and each other from aggression. Ben Wallace, the Defence Secretary, said he detected a “whiff of Munich” about attitudes to sovereignty, with some European countries apparently content to negotiate away Ukraine’s territorial integrity as they did Czechoslovakia’s in 1938.

Appeasement was arguably necessitated by the unpreparedness of European nations, including Britain, to the threat posed by Hitler. Today, reluctance to confront Putin is strongest in countries beholden to Russia for their energy supplies which have also scrimped on their defence spending for decades.

Nato is the ultimate protective shield for Europe but it needs the contributions of all to work effectively. By some measures, the US pays 75 per cent of the alliance’s total defence spending, much of which is primarily intended for the defence of Europe. With their attention focused much more now on China, successive US presidents have insisted that Europe shoulder a bigger share. It is almost eight years since an agreement following a conference in Cardiff proposed a minimum spend of two per cent of GDP by all Nato countries.

The UK meets this commitment, as do the Baltic states and Poland. But the EU’s biggest economies, including Germany, Italy and Spain, still fail to do so, though France is on the borderline and has a nuclear deterrent which others do not.

They blamed austerity after the financial crash for not spending more and now put the blame on the cost of the pandemic. But there were years of recovery in between when wealthier states still refused to boost their military spending. If Europe is not prepared to defend itself then it cannot be surprised when its weaknesses are tested by an aggressor.