You saw the first plane crash, and then people came in and started to brief me on it, and then of course it became clear a short time afterwards that this was not simply a terrible accident but was almost certainly a terrorist incident, and then everything changed.

I thought instinctively right from the beginning that it was going to be huge, that it would be a defining moment for American foreign policy, and their attitudes towards the world.

'Brutal fact'

But also that it presented a momentous challenge to the world at large because it was clear that this was directed at America, but at America as a symbol of the Western world and the values we held.

And there was no doubt in my mind, one that we had to stand very, very closely with America, that America should realise straight away that it wasn't alone in such a situation. And number two that we should regard this as if it was an attack on any of us, and all of us.

Here is America, subject to a brutal terrorist outrage killing thousands of its citizens. There is no, ‘Well let me see for a moment which side I am on’. I am often somebody who likes to see both sides of an issue and to feel my way consensually.

But there are moments, and you have got to recognise this in politics, where there is no meeting of minds.

As I said myself a few weeks later, the people that carried this out didn't have a negotiating strategy. There wasn't a dialogue that you were going to get into. There wasn't a change of heart that was going to come about as the result of talking to them.

There was the simple brutal fact that they had annihilated thousands of people without any compunction at all, and indeed would have annihilated many thousands more had they been able to do so.