Sixty-five years ago, this month, Nato was born into a dangerous world. As the Soviet shadow deepened across Europe, 12 nations from both sides of the Atlantic committed to individual liberty, democracy, human rights and the rule of law were determined to stand together to safeguard their security. Those nations were Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, the United Kingdom and the US. They took the most solemn pledge that any country can take: An attack on one would be viewed as an attack on all. Today’s Nato brings together a unique combination of the world’s strongest democracies with an integrated military structure, a permanent political decision-making process and a network of more than 40 partners from around the world. It is where Europeans and North Americans consult, decide and act every day on security issues that concern all Nato members.

We have learned much from the last 20 years of challenging operations, from Afghanistan to Kosovo, from Libya to the Horn of Africa. We are now more efficient and effective than at any time in Nato’s history. We still live in a dangerous world and the threats are more complex and unpredictable than 65 years ago. Some are new: Cyber and missile attacks.

Others are age-old: Attempts to redraw borders by force. What has not changed is Nato’s commitment to its fundamental values and purpose. Nato’s motto remains: All for one, one for all. That solidarity is clear in Nato’s response to Russia’s illegal aggression against Ukraine and its continued breach of international law. Thanks to allies from both sides of the Atlantic, Nato has more than doubled the number of fighter aircraft policing the airspace of the Baltic States. Nato is patrolling the skies of Poland and Romania with Awacs early-warning aircraft and allies have boosted their presence in the Black Sea. Nato is united in its determination to deter threats and to defend any ally at all times. Nato has also strengthened its support for Ukraine and other partners in the region.

And Nato members have suspended cooperation with Russia; there can be no business as usual. Nobody in Nato wants a return to the Cold War, but the members see the Kremlin trying to turn back the clock and carve up Europe into new spheres of influence. Nato must stand up for its values, on which it has have built a new and better Europe and for the system of international rules that has underpinned prosperity and predictability.

This September, Nato will hold a summit in Wales — a pivotal meeting at a pivotal time. The Nato members will make sure that they remain strong at home, active in managing crises, and engaged with their partners around the world. Today’s crisis shows that defence matters as much as ever. So every ally needs to invest the necessary resources in the right capabilities.

That means modern equipment, intensive training for Nato forces and closer cooperation among Nato allies and with the partners. I know how challenging this is in today’s economic climate, but the security climate makes it vital. In the long run, a lack of security will be more costly than investing now and Nato owes it to its forces and to broader society. All members benefit from Nato’s protection; they all must be able to contribute to it. The alliance has kept the members safe for 65 years.

The bond between the democracies of North America and Europe remains the bedrock of Nato’s collective security. Nato has stood the tests of the past. It is ready to face the future.

— The Telegraph Group Limited, London, 2014

Anders Fogh Rasmussen is the secretary-general of Nato.