American Defence Secretary Donald Rumsfeld's no-nonsense approach has propelled him through a 30-year career, winning admiration and respect among many in the United States.
Donald Rumsfeld is one of Mr Bush's most experienced officials
But his blunt style has periodically angered and alarmed others.
His latest remarks - on the possibility that the US might go to war with Iraq without the UK - sparked confusion and shock in the British Government.
In January Mr Rumsfeld's words triggered fury in France and Germany after he bluntly dismissed their opposition to a war against Iraq:
"Germany has been a problem and France has been a problem. But you look at vast numbers of other countries in Europe... they're with the US.
"You're thinking of Europe as Germany and France. I don't. I think that's old Europe", he told a White House press conference.
Mr Rumsfeld's international profile has risen considerably since the 11 September terror attacks on New York and Washington. He has reputedly not taken any time off since then, and regularly works 14-hour days.
He has vigorously fended off criticism of the US war on terror.
'He'll live or he'll die'
In February, he took a typically forthright view on whether al-Qaeda figurehead Osama Bin Laden would be found:
"I don't know it matters how confident I am," he told reporters.
"He either will or he won't. He'll live or he'll die. He's either in Afghanistan or someplace else, or dead. We intend to find him. If he's findable."
Defending the handling of detained al-Qaeda and Taleban members following the war in Afghanistan, Mr Rumsfeld came out with a suitably direct summation:
"Will any single prisoner be treated humanely? You bet. Will they be restrained in a way so they're less likely to be able to kill an American soldier? You bet. Is it inhumane to do that? No. Would it be stupid to do anything else? Yes."
Mr Rumsfeld's approach to politics, international diplomacy and life in general is collected in a slim volume well known to US political commentators entitled "Rumsfeld's Rules".
The document, a collection of phrases and sayings uttered or written by the defence secretary, members of his family and colleagues, is divided into chapters with such to-the-point titles as "Doing the job in the White House", "On business", and "Life."
'Put your head down'
A telling inclusion is a quotation from Professor Lewis Sarrett: "Persuasion is a two-edged sword - emotion and reason. Plunge it deep"
In another section, Mr Rumsfeld advises: "Amidst all the clutter, beside all the obstacles, aside from all the static, are the goals set. Put your head down, do the best job possible, let the flak pass and work towards those goals."
While this plain speaking has won Mr Rumsfeld plaudits, others have criticised his no-nonsense approach.
"All the macho talk in the world can't replace the tact and understanding of sensitive situations that international diplomacy requires," an unnamed Pentagon official told the PA News agency.