On the one side we have a flamboyant and unpredictable character who is attempting to lead his country via Twitter, and on the other the steely-eyed ex-KGB agent who is not above a bit of macho posturing of his own, usually involving taking his shirt off. As a friend of mine commented: “What could possibly go wrong?” Well, let’s hope it doesn’t, because in terms of world peace and security this is probably the most important meeting of world leaders in recent years. The bedrock of European peace since 1945 has been the Nato alliance and, in particular, the US nuclear umbrella. It was American resolve – and billions of dollars from US taxpayers – that defeated the Soviet empire in the Cold War and liberated millions in eastern Europe from the yoke of socialist oppression and grinding poverty. But today that security is under increasing threat. Uniquely among US presidents, Trump has been hugely sceptical of the value of Nato, calling it “obsolete” while on the campaign trail, and saying it is “costing us a fortune”. He has a point. The US contributes more than 70 per cent of total defence spending by Nato countries and only five of the 28 members of the alliance – the UK, US, Greece, Poland and Estonia – have hit the target of spending two per cent of GDP on defence. The rest have been happy to sit on their hands and let other more responsible countries take the burden. But why should a taxpayer in Hoboken, New Jersey, pay more to defend Europe from Russian aggression than a taxpayer in Hamburg? Thankfully Trump has slightly softened his stance since taking office, and has since made his support for Nato clear, but he has emphasised that European countries must begin to pay their way. That seems entirely fair. And the meeting today with Putin is an ideal opportunity for the US President to make clear America’s commitment to European security and give the Russian leader fair warning that Nato will not tolerate any further Russian shenanigans in Ukraine or the Baltic states. It is also a chance for the two countries to combine forces and increase co-operation to defeat a joint enemy – Islamic extremism. Trump has his work cut out. American credibility took an enormous hit when Barack Obama laid out strict “red lines” to Syria’s Bashar Assad over the use of chemical weapons, only to meekly capitulate when those lines were crossed. This catastrophic weakness emboldened the enemies of liberty, and in the total absence of American leadership in the Middle East we have seen Russia, Iran and Islamist jihadis rush to fill the vacuum. Trump now has a lot of hard work to do to restore the US’s reputation for strength and dependability, and today’s meeting is vitally important in that process. And this matters to us all. As far as European security and peace goes, Nato is the only game in town. The alternative – all the silly, grandiose plans for an EU army – are nothing short of preposterous. EU countries are happy to have a joint army – as long as someone else pays for it and someone else does the actual fighting. But now that the UK is leaving the EU there are simply no volunteers to fulfil those roles. And as their dream of a European superstate crumbles around their ears, the EU-fanatics are quarrelling bitterly with each other. Only this week European Commission President Jean-Claude Juncker slammed the European Parliament as “totally ridiculous” and “not serious” after fewer than 30 MEPs, out of a total of 751, bothered to turn up for an important debate on the migrant crisis. The idea of any of these clowns defending anything beyond their expense account lunches is simply laughable. We need Nato today as much as we ever have. Let’s hope Trump can rein in his excesses and show Putin that the US and Nato can be dependable partners for security and for fighting terrorism, but also implacable and ferocious foes if Russia continues to threaten the hard-won peace in Europe.