Leaders of the 29 members of the North Atlantic Treaty Organisation (Nato) are gathering in Brussels for the annual meeting of the mutual defence group at a time when it faces an uncertain and turbulent future. Over the seven decades since it was set up by 12 founding nations in 1949, Nato has assured the mutual defence of each of its members, finding strength in its numbers and under the reality for its adversaries that an attack on one was indeed an attack on all.

It’s worth remembering that Nato was formed in the aftermath of the Second World War while Europe and the combatants in that cataclysmic six-year struggle were grappling with the fallout of that conflict and the dawn of age where atomic weapons unleashed a new type of warfare. It also was established at a time when the Iron Curtain was being drawn across the continent, where the Soviet Union and its Communist satellite republics entered a Cold War based on ideological lines, pitting East against West.

And as the leaders meet in Brussels now, this history is indeed important to remember. The success of the organisation is that its very presence and unity was a source of strength in facing down the might of the Soviet Union. Those of us of a certain age can remember tense standoffs along that Iron Curtain, where thousands of tanks and millions of men faced off in a state of anxious readiness. And thanks to Nato, that Iron Curtain fell and the Cold War ended — all without a shot being fired between East and West in Europe.

It’s also worth remembering that the only time over its seven decades that the mutual defence articles became operative were as a direct result of the terror attacks on the United States on September 11, 2001. At its time of greatest need, Washington had allies who were willing to stand by it and stand united.

Since its 2014 summit, Nato members have committed to spend 2 per cent of their GDP on defence by 2024. While living up to that is a source of irritancy in Washington, that itself cannot be a reason to undermine Nato’s unity. Indeed, for the Baltic states who rely on the organisation, it remains critical. While the US, the United Kingdom, Estonia and Greece have reached that 2 per cent goal, the other Nato members still have six years to do so, and it cannot happen overnight — just as the Cold War was not won overnight.