As I wandered along the first floor of the Pentagon, past the portraits of secretaries of defence of yore and the framed newspaper front pages proclaiming America's great military victories, I considered the words of a former president.
It was Dwight D Eisenhower, who warned, in his farewell address of January 1961: "Our military organisation today bears little relation to that known by any of my predecessors in peacetime, or indeed by the fighting men of World War II or Korea . . . This conjunction of an immense military establishment and a large arms industry is new in the American experience. We recognise the imperative need for this development. Yet we must not fail to comprehend its grave implications. In the councils of government, we must guard against the acquisition of unwarranted influence, whether sought or unsought, by the military-industrial complex. The potential for the disastrous rise of misplaced power exists and will persist."
There is no record of Eisenhower's words in the Pentagon. There is no record of failure. The memory of Vietnam has been excised. Soon pictures of the "liberation" of Baghdad will adorn the walls. For Donald Rumsfeld and Paul Wolfowitz, the operator and the brain, there is a sense of total vindication. They have seen off the armchair generals who called into question their military strategy in those few days when progress was slow. And they have seen off their political critics. Their position in the Washington power play is now unchallenged.
To visit the Pentagon, the world's largest office building, is to appreciate what has happened to American politics and to understand Tony Blair's terrible dilemma.
For all Rumsfeld's pre-war misgivings about our Prime Minister, it is a good time to be British. We had telephoned the press office ahead of time to check arrangements. The woman there said at the end of the call: "Just let me tell you, we love your Tony Blair." As I was waiting to be escorted into the building, I bumped into an acquaintance from the American Enterprise Institute, a right-wing think-tank very much in vogue. His party was going in for one of its regular lunches at the Department of Defence. He introduced me to a colleague. "You Brits have been great, except for the BBC," she said. I did not say I was on assignment for the Baghdad Broadcasting Corporation.
There are no frills about the Pentagon. The only acceptable form of self-criticism is the standard of the canteen food. By way of "improvement", a new contract has been signed with McDonald's, Pizza Hut and Taco Bell to open restaurants within the complex to feed its 23,000 employees.
Rumsfeld and his people get in the building at 6am. Their offices are comfortable but not lavish. There is concrete here, not marble. A building put up in a hurry over the marshes of Arlington, Virginia, in the Second World War has only now been fully restored following the attack on it on 11 September 2001. It is surrounded by tanks and other heavy armoury.
The military-industrial complex that the Soviets aspired to, that Eisenhower feared, has reached its apogee under this administration. US defence spending is larger than that of the next ten countries put together. The Iraq war proved that the technology is "smarter" than it has ever been. But the conflict was more important to the psyche of the generals than that. It laid to rest the Vietnam syndrome that had persisted for 30 years. The fear of war that Bill Clinton had in deploying American forces in Kosovo, that George W Bush continued to have to a lesser degree in Afghanistan, has been overcome.
Half a mile away, across the Potomac, there is no such confidence at the State Department. Decades of traditional diplomacy have been torn up. This is the world that Blair and a succession of British prime ministers and foreign secretaries are used to. Now, the liberal establishments of Washington and New York are struggling to keep pace with the new realities.
The three main television networks have lost about two million viewers a night to the new cable entrants Fox News (owned by Rupert Murdoch's News Corporation) and MSNBC (owned by Microsoft and General Electric). Fox's formula - its deference to the Bush administration, its discarding of objectivity, its emphasis on patriotism and scorn for dissent - has proved a huge hit. It has worked for viewers, it has worked for the stations and it has worked marvels for the military.
The man who devised the system of embedded reporters, a man called Bryan Whitman, the number two at the press office, is the toast of his bosses. The "embed" idea will be repeated next time around. Journalists who want to go it alone, the so-called "unilaterals", can do so - at their own risk.
And there will be a next time around. It is just a question of where. It is not only Rumsfeld and Wolfowitz who are on the march. The Department of Defence, once seen as the annex of government stuck out across the river, has rediscovered its voice as an institution. With its confidence high and with its influential supporters in the media, in the business world and in the arms industry, it demands to be heard - and it will be.