In a world of growing security challenges, Nato remains an indispensable security alliance

There has never been a time more ill-suited to the display of differences among transatlantic allies

Nato heads of state and government will convene for an annual summit in Brussels this week. Reuters

This week, leaders and representatives of the member states that comprise the North Atlantic Treaty Organisation will gather in Belgium for the annual summit of the most formidable security alliance in human history. Tension suffuses the air in Brussels. Not since the group's foundation in 1949 have graver doubts been expressed about its utility. As a candidate for the American presidency, Donald Trump dismissed Nato as "obsolete". After entering the White House, however, he hastily recanted that remark and affirmed his commitment to the alliance. But not everyone is persuaded.

The conditions in which a transatlantic security pact was forged seem too remote to too many people at a time when isolationist nationalism is once again gaining popularity – but it would be a profound mistake, a deadly delusion, to believe that the challenges and threats that necessitated Nato's formation have dissipated or disappeared. The Second World War concluded with the Soviet Union's footprint spread across vast swathes of Europe. Democratic voices were muzzled, nations invaded, human aspirations ruthlessly stamped on as the Iron Curtain fell over lands that had just emerged from history's bloodiest confrontation. If the Marshall Plan embodied Washington's vision to prevent another conflict by rebuilding Europe and bringing prosperity to its peoples, Nato expressed the rock-hard determination of the US and its allies to defend themselves against aggression. Its presence, serving as a deterrent, averted an outright clash between the superpowers during the Cold War.

The collapse of the USSR, however, did not make Nato redundant; it infused it with fresh purpose. Nato’s membership of 29 states includes a dozen former communist nations. To them, the organisation is much more than a security alliance. Their acceptance into it is still regarded as a fulfilment of a long yearning for freedom, and many of them have made tremendous sacrifices to uphold its mission.

Nato's intervention in the former Yugoslavia halted what was poised to be yet another genocidal campaign by Serb nationalists. The fact three former constituent republics of Yugoslavia – Slovenia, Croatia and Montenegro – are now members of Nato is a measure of the distance Europe has travelled under the blanket of security provided by it. The attacks of September 11, 2001, prompted Nato to invoke Article 5 – which calls for collective action – for the first time. And Nato soldiers subsequently laid down their lives in Afghanistan.

Despite this history, a serious deficit of trust overhangs Nato. Europeans, operating against the menacing milieu of a resurgent Russia, are anxious that Mr Trump is more receptive to Vladimir Putin, the Russian president, than Washington's most steadfast allies. Although Mr Trump's demand that Europeans raise their defence expenditure to meet Nato's guideline of 2 per cent by 2024 is not without merit, there has never been a time more ill-suited to the display of difference.