Donald Rumsfeld is a forthright, even abrasive man whose popularity has fallen sharply as the war in Iraq has failed to turn out as the Bush administration predicted.
By Richard Allen Greene
BBC News, Washington
But even so, the recent wave of criticism of the US defence secretary by former top-ranking generals is all but unprecedented in the past generation.
At least seven retired generals have questioned his abilities in the past month, sparking a firestorm of debate and forcing the president to interrupt a holiday weekend to issue a statement of support.
Mr Rumsfeld rarely seems concerned by criticism
"It is unusual for retired military officers to speak out in public and through the media against a current defence secretary - there is little doubt about that," says Harry Disch, the president of the Center for Media and Security.
While there may be open discussion about specific military issues such as readiness or modernisation, this debate is different, he says.
"What is unusual about the current criticism of Donald Rumsfeld is that it takes on a personal tone regarding judgement, management style, and, most importantly, competence."
Going public with his criticism of Mr Rumsfeld was "gut-wrenching, the hardest thing I have ever had to do in my life", ones of the generals has said - but he retired from the service on principle in order to do so, he says.
"If I were still in uniform, I couldn't do this. I would be arrested," former General John Batiste told the BBC News website.
CRITICAL RETIRED GENERALS
Gen Wesley Clark, Army
Gen Charles H Swannack Jr, Army
Gen John Riggs, Army
Gen John Batiste, Army
Gen Anthony Zinni, Marines
Gen Gregory Newbold, Marines
Gen Paul Eaton, Army
Like the other retired officers, he says the US did not plan properly for the occupation of Iraq.
"Strategically it has been a disaster, primarily because of a series of very bad decisions. The leader of the department of defence has to take responsibility," he says.
Mr Rumsfeld has given no indication he is considering stepping down, and other retired officers including Richard Myers - the top US general until last year - have lent him their public support.
Some former officers go even further, attacking the generals who are calling for Mr Rumsfeld to go.
Douglas Macgregor, a retired Army colonel who now works as a military analyst, says the critics are trying to pin blame on the defence secretary for their own errors of planning and execution.
"The generals see it as everyone else's fault other than theirs," he says.
Critics doubt there are enough troops on the ground
He says Mr Rumsfeld set goals for the military to accomplish and left the generals to make the battle plans - as he should have done.
Their failures, not the defence secretary's, have got the US bogged down in Iraq, he argues.
He dismisses the oft-heard judgement that the Americans have too few troops on the ground.
"One would expect a more enlightened view from those who were in Vietnam, since we poured hundreds of thousands of troops into Vietnam and we lost.
"The bottom line is that many of these general officers are being both dishonest and hypocritical. Removing Rumsfeld isn't going to change anything."
But not all the generals calling for Mr Rumsfeld to go were serving during the invasion of Iraq, experts point out. At least two retired the year before it and presumably do not see their personal reputations as being on the line.
And sources say as many as two dozen other retired top-ranking officers may be on the verge of coming forward to join the public critics - some of whom have been retired for 15 years.
Mr Disch of the Center for Media and Security lists many possible reasons the Rumsfeld critics have come forward at this point, ranging from true belief in what they are saying to fears that the US military will be caught in a civil war in Iraq.
Ultimately, however, he says the reason - or reasons - for their actions may be irrelevant.
"By weighing in, regardless of their intention, it will help to shape opinions, particularly to those who are still sitting on the fence."
And - as he points out - this is an election year.
Whether George W Bush's Republican party retains control of Congress will have much to do with American opinion about the war in Iraq - a factor he will have to take into account as he considers Mr Rumsfeld's future.