Tom Tugendhat is Conservative Candidate for Tonbridge and Malling. A former reservist army officer who also worked for the Foreign Office, his last post was military assistant to the Chief of the Defence Staff.  He now runs Lashkar & Co, a strategy consultancy.

Since the end of the Second World War, NATO has been an amazing success.  In the words of Hastings Ismay, its first Secretary General, it has kept the Russians out, the Americans in and the Germans down.  That’s no mean feat when you look at the record of Soviet expansionism, American isolation and German aggression over the past century.

But today it faces a threat that it cannot defeat – austerity. European governments are penny-pinching NATO away.  Even those screaming loudest that NATO should act against Russia’s invasion of Crimea are doing little to resist what they argue is a new imperial dream.

Lithuania or Latvia stump up less than one per cent of their GDP on self-defence, but say that others must provide the planes to defend them against potential Russian incursion. Only Estonia, whose forces serve bravely alongside the UK on operations in Afghanistan, spends NATO’s target of two percent of its GDP on defence, but they’re the exception.

Poland, which will soon receive a detachment of RAF Typhoons, spends only 1.8 per cent, while Romania and Bulgaria – both of whom are calling for NATO to face down Putin’s aggression, spend only 1.4 pe rcent of their own money.  At least that’s more than Hungary’s paltry 0.9 per cent.

Not only those closest to the front should be doing more, if the alliance is to mean anything then all should carry their share of the burden. But Spain and Italy spend only around one per cent and are cutting their budgets further while Germany, Europe’s powerhouse, puts up a mere 1.3 percent.

This isn’t simply an accounting exercise. It is the heart of the problem with NATO. Since the end of the Cold War, European countries have been living in the shadow of Washington’s expense, and the Americans have finally had enough. Today, Obama is looking inward at healthcare and the economy and though he may be drawn into Europe’s problems again, as he was over Libya, he too is cutting back on the military.

Because the truth is that this is a European problem. 70 years of peace has lulled capitals across the continent into the illusion that war is a matter of choice. They do not appreciate that defence is a continuous act or that waiting to be attacked is morally questionable.  It means expecting your own people to bear the burden of aggression rather than looking to do your best to prevent it.

That requires action. Not attacking others, but ensuring that potential aggressors know a military option will lead to their defeat, forcing them down the road of diplomacy instead. The irony is that the most effective armed forces are those that are never used. But try explaining to a Treasury mandarin that troops ‘only’ training are actually serving a purpose – deterrence – and that is cheaper, better and easier than the alternative.

Britain’s most peaceful period at home, the century before the First World War, was bought with spending on the Royal Navy. It is no accident of history that Britain went unchallenged then nor that NATO is being confronted today. Nor that actions like the Falklands War were studied by the Soviet General Staff.

Britain’s victory in the South Atlantic would have been difficult for the might of the USSR and impossible for any of her allies. It was one of many factors that helped to convince the Kremlin that a military victory was impossible and reform was the only answer – the most successful peaceful victory in the history of warfare and unimaginable only a decade earlier.

But today that aura of power, key to any defensive stance, has eroded and NATO’s talk of smart defence weakens it further. Talk of sharing capabilities – which in reality means no one is responsible because everyone relies on everyone else – has justified in doctrine the inability to act.

That leaves the US, spending 4.4 per cent, carrying the burden of Western defence.

At a time when many say that Crimea is a forerunner to further aggression in Ukraine, Transdniester and other parts of Russia’s so-called near abroad, NATO needs to remember what it is for. The alternative is to allow our competitors to think a military solution is cost free. The perception of an easy victory makes challenge, and therefore conflict, more likely.

NATO still has a crucial role. It should be the bastion of free nations who are committed to a peaceful world order. Today that should include some Gulf allies and others, like Australia and New Zealand, not just the underfunded Europeans. But for that to be a possibility, Jens Stoltenberg, NATO’s next Secretary General must show leadership.

If he can’t, the burden will not be shared and the organisation will stagnate. Because from Washington’s perspective, the alliance looks very one-sided.