25 years ago, the world stood still. Riveted to screens, we watched in horror and disbelief as the Twin Towers fell.

Today, we remember. The nearly 3,000 people who left home that morning and never returned. The firefighters, police officers and first responders who ran into the smoke and dust and saved countless lives. The families who have borne the weight of loss for a quarter of a century.

9/11 was the most consequential event of the turn of the century.

And it revived the importance of alliances and collective security. Europe knew immediately where it stood. We stood with America. For the first and only time in its history, NATO invoked Article 5. An attack against one was an attack against all. We stood together in defence of the principles that unite us across the Atlantic: freedom and democracy.

Those who carried out the attacks wanted to spread fear far beyond New York, Virginia and Pennsylvania. 25 years later, we know they have failed. Our democracies endured. Our societies remained free. And the ideology of terror failed to impose its grip on our world.

Today, the threats we face have changed. We live once again in troubled geopolitical waters, marked by great-power rivalry, war and confrontation between states. But the lesson of September 11 remains. In moments of danger, our alliances matter. Our unity matters. And the values we choose to defend matter.

Where the Twin Towers once stood, two columns of light now rise into the New York sky. They defy oblivion. They carry the memory of those we lost. And they remind us that light triumphs even on the darkest of days. Photo by Michael Foran, Wikimedia commons.