Tony Walker, in the Australian Financial Review (fApril 17, 2004):

History seems to offer no lessons for America as it repeats a number of the serious errors it made in Vietnam one of the most notable being the lack of an exit strategy.

On August 5, 1964, US president Lyndon Baines Johnson sent a message to Congress asking for war powers to confront a communist menace in Asia. "America keeps her word. Here, as elsewhere, we must and shall honor our commitments. Our purpose is peace. We have no military, political or territorial ambitions in the area," Johnson wrote.

Forty years later, the same words could just as easily have been uttered by US President George Bush regarding another conflict in another time and another place. Indeed, the Iraq war resolution of late 2002 exposed the same sentiments.

In the so-called Tonkin Gulf resolution (US warships had been attacked in the Tonkin Gulf in the summer of 1964) of the US Congress of August 7, 1964, the Senate and the House of Representatives backed the then president as commander-in-chief, to "take all necessary measures to repel any armed attack against the forces of the United States to prevent further aggression".

Eleven years and 58,000 American lives later, the US exited from Vietnam after being consumed by the sort of agonising debates swirling about Washington now regarding Iraq. But the difference between now and then, apart from the obvious distinctions between Vietnam and Iraq, is that America has a model to look back on the Vietnam example.

Unfortunately, it seems to be in the process of repeating some of the same errors, including a flimsy pretext for an invasion; lack of clarity in its objectives; gross miscalculation about attitudes on the ground to its role not as liberators, but as occupiers; unreasonable confidence invested in local surrogates; and finally lack of an exit strategy. This last error is, arguably, the most significant.

In the mantra of the moment that the US cannot afford to fail (Bush in his televised press conference this week described failure as "unthinkable"), that it must stay the course, that it cannot cut and run, that the whole future of Western civilisation is at stake, what tends to be subsumed in the debate is the "what if" question.

That question has to do with the "unthinkable", in George Bush's words failure. Of course, in such complicated circumstances failure is sometimes difficult to define. What constitutes failure? When might it be reasonable to assess (success or) failure? What criteria should be used to judge failure?

Back in 1964 there were not many voices either who were contemplating failure: it's sometimes forgotten that the American media and intelligentsia were overwhelmingly for the Vietnam war in its early stages.

In the Cold War atmosphere of the time, arguments about the need to contain the spread of communism, to impede the fall of dominoes, prevailed, more or less.

Then it was the contest with the Soviet Union (and China) which shadowed the debate and complicated perceptions. Today it is the war on terror, the threat of militant Islam in the wake of the September 11, 2001, terrorist attacks in the US that burdens discussion.

When a country is at war, questions like "what if" tend to be muted.

To be sure, there were a few voices in 1964 who separated themselves from the pack: Walter Lippmann, the distinguished newspaper columnist, and Hans Morgenthau, the historian, made their reservations known, the latter in his 1965 book Vietnam and the United States.

It's interesting to read today Johnson's private taped conversations with senior aides about his views at that moment of history of various individuals, Lippmann included. Johnson was extraordinarily sensitive to criticism and quite fussy about details raised by individual columnists.

Those were the days when the press, as opposed to television, was relatively all-powerful. Now, the chatter of the news channels with their gargantuan appetite for talking heads tends to drown even the most thoughtful commentary.