Always ready to joust with the Pentagon press corps, Rumsfeld has been on the defensive despite the gathering pace of the US offensive on Iraq, and sometimes letting his irritation show.

The war plan he largely inspired has endured some tough criticism both from commentators and former generals, in addition to complaints from officers on the ground in Iraq.

Experts have said that, even if US victory is assured, the US military was overoptimistic about the level of resistance to be expected and that Rumsfeld had tried to go to war "on the cheap" with insufficient ground troops.

On Tuesday, General Richard Myers, chairman of the Joint Chiefs of Staff, staunchly defended his boss, qualifying the war plan as brilliant.

In an editorial Wednesday, The New York Times noted however that statements by Rumsfeld and Myers "have ranged from irritated to nearly apoplectic when they have responded to criticism."

The Times said Rumsfeld "has bruised a lot of egos" in his time. "Right now, when soldiers' nerves are edgy and the public is concerned about the pace of the war, he can use all the support he can get among the military brass."

Rumsfeld has a "very strong personality," that serves as a "lighting rod to defuse problems," said Theresa Hitchens of the Center for Defense Information.

"But he has a very strong position within the administration," she added.

It has become public knowledge that Rumsfeld and his friend US Vice President Dick Cheney -- two leading "hawks" in the Bush administration -- were unwilling to seek a diplomatic solution to disarm Iraq as sought by Secretary of State Colin Powell.

Under cover of anonymity, military officers have criticised Rumsfeld for being arrogant, and wanting to get too involved in strategy and tactics, such as in the case of the US-led war in Afghanistan.

Never satisfied, the defense secretary bombards generals with demands and often asks them to re-do their work.

Although without specifically naming him, Republican Senator Chuck Hagel said recently: "When your battlefield commanders who are there, who are commanding troops in the middle of the battle are saying certain things, the civilian leadership must be very careful not to be publicly dismissive of that.

"They should listen to it carefully," Hagel added.

Rumnsfeld's press briefings at the Pentagon have become prime time events because of the war. The briefings, alongside speeches by President George W. Bush, are simultaneously translated into Arabic and broadcast to Iraq.

Seen by US female magazines as telegenic, despite his 70 years, Rumsfeld has also been dominating the Sunday talk-shows, with his irony-tinged self-assuredness, his ripostes, his frankness in refusing embarrassing questions.

"Rumsfeld, turning the briefing into high art," the Washington Post recently wrote of him.

Some commentators, like Seymour Hersh of the New Yorker magazine, compare him to Robert McNamara, the former defense secretary who also had an air of self-assuredness like Rumsfeld.

McNamara was also involved in getting the United States deeply embroiled in the war in Vietnam.

Rumsfeld got involved early in politics, and was first the defense secretary when Gerald Ford was president (1974-1977). A wealthy industrialist in his own right, he was invited back by Bush in January 2001 to help set up a US anti-missile defense system.

He is, in fact, convinced that the United States needs strong defenses against so-called "rogue states" -- among them Iran and North Korea -- and terrorists.

A number of his comments have also had shock value, such as when he lumped Germany and France together within "old Europe" and even fleetingly embarrassed top US ally British premier Tony Blair by suggesting the United States was ready to go to war without Britain.

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