By Paul Reynolds
BBC World Affairs correspondent
The flags of many nations fluttered in the cold Washington wind behind President Bush as he announced that the second stage of his declared war on terrorism had begun.
And his speech pointed towards the next actual and potential battlefields of that war: the Philippines, where US forces are helping to counter Muslim guerrillas; Georgia, the remote former Soviet state from where Stalin came which faces a threat on its even remoter border; Yemen, which Mr Bush said would not be allowed to become a second Afghanistan and, above all, Iraq.
Mr Bush reflected the mood of the country, which six months on, is still angry and combative
He did not name Iraq. He did not have to. Everyone knows that Iraq is on the list. The only questions are what action will be taken and when. Mr Bush sought to provide an answer to the question why.
He claimed that it was now too dangerous to allow rogue states to develop weapons of mass destruction because these could fall into the hands of terrorists and then "blackmail and genocide and chaos" would be unleashed.
In the face of such a threat "inaction is not an option" Mr Bush declared.
This link between terrorism and states with weapons of mass destruction - chemical, biological and nuclear - was at the heart of his speech.
Bush did not mention Iraq, but he did not have to
It is the justification Washington and whatever allies it can get will use if they decide to act against Iraq.
And it seeks to mend a hole in the American argument. This is that there is no evidence linking Iraq to al-Qaeda and 11 September. Now no evidence is apparently needed.
Elsewhere in his speech, a sombre Mr Bush reflected the mood of the country which, six months on, is still angry and combative, heightened by the recent fighting in the mountains of eastern Afghanistan.
Mr Bush's approval rating is around or more than 80%. Whatever lies ahead, Americans are, for the moment at least with him.
The determination of the country to see this through (and nobody really knows where it is leading, of course) has been made even more solid by an extraordinary television documentary of events inside and outside the World Trade Center on 11 September.
The country is still in mourning
The film went out in the United States on the eve of the six-month mark. The BBC will show it on the full anniversary. It makes searing viewing.
The film was the work of two French brothers who were making a documentary about a rookie firefighter at a fire station which happened to be nearest the WTC.
They were there for months. On the morning of 11 September, one of the brothers went off with a crew to investigate a smell of gas. His camera suddenly picks up the first plane as it smashes into Tower One. That film had been seen before. What happened next had not.
The camera follows the firefighters into the lobby of the tower. Bangs are occasionally heard - the bodies of those who jumped landing on the ground outside.
In the dark
There is chaos in the lobby. Nobody knows what is really happening. They do not know that a second plane has hit the other tower. But calmly and bravely, the crews do their job - they start climbing the stairs to get to the fires.
Then, there is a tremendous noise, but again, they are in the dark - in two ways. They do not realise that the other tower has collapsed and the light is dimmed by the cloud of dust as they struggle to escape.
The film ends on a more upbeat note. Everybody at the firehouse survives, including the two brothers, who embrace in a moment of relief.
Such a film is one reason why, whether the rest of the world likes it or not - or understands it or not - Americans are not letting this whole thing go.