The failure to stop 9/11 was a catastrophe. But even bigger mistakes were made in its aftermath

The September 11 2001 terrorist attacks were unlike anything the world had seen before.

For America, and the watching world, September 11 (or 9/11) seemed most like a Pearl Harbour moment – a devastating surprise attack by a distant enemy that demanded a response.

But here the distant enemy was not a nation state in the middle of war, it was a ragtag collection of rebels living in mountain hideouts, long underestimated and widely misunderstood.

It took Hollywood movies to convey the horror of Pearl Harbour .

But hundreds of millions around the world watched, via live satellite TV feeds , in disbelieving horror as fully laden commercial aircraft slammed into the first World Trade Centre tower in New York.

Hundreds of millions more saw the second tower hit, then witnessed both massive skyscrapers collapsing faster and more completely than seemed possible.

Read more: 9/11 conspiracy theories debunked: 20 years later, engineering experts explain how the twin towers collapsed At the time, this felt like a moment that changed everything – a hinge point in history on which so much would turn.

Twenty-five years later, that devastating intuition has been confirmed through a cascading series of grim events and tragic mistakes.

Could the September 11 attacks have been prevented? In September 2026 we live in a world of uncertainty and change.

Geopolitics, technology and the physical world are experiencing rapid transformation that fascinates and terrifies in equal measure.

Much of this would have occurred without September 11, but there is a sense in which that day changed all these things.

The collapse of 80 years of global order cannot be said to have simply resulted from the world’s biggest terror attack, but it certainly played a role in triggering a series of responses that has changed all the nations involved.

Could the September 11 attacks have been foreseen and prevented? Absolutely.

Counterterrorism intelligence has evolved massively over the past 25 years.