Donald Rumsfeld's Pentagon is at the centre of the new 'war' on terrorism

Like Secretary of State Colin Powell and Vice President Dick Cheney, Mr Rumsfeld is a veteran of previous administrations, having served as secretary of defence once before, during Gerald Ford's presidency in the mid-1970s.

In his memoirs, Henry Kissinger described Mr Rumsfeld as a "skilled full-time politician-bureaucrat in whom ambition, ability and substance fuse seamlessly".

Since the new administration came to power, Mr Rumsfeld has been leading the Pentagon's review of the military.

New strategy

That means coming up with a new military strategy for the 21st Century.

This will probably mean ditching the old principle that the US should be able to fight two major conflicts simultaneously.

He is expected to aim to reorganise the armed forces, re-focus foreign affairs away from Europe towards Asia and replace old weaponry - all within a heavily scrutinised budget.

F117 Stealth fighters are at the forefront of US military technology

Now, waging war against global terrorism has also been added to the list.

To help him, Mr Rumsfeld's armed forces possess a budget equal to those of the world's next eight military powers combined.

Before 11 September, the idea of a devastating terrorist attack on the US mainland was only ever really considered a possibility by paranoid Pentagon generals.

Events have shown otherwise. Although concerned more with attacks from states rather than terrorists, Mr Rumsfeld has been warning of new threats to American security for years.

While many, in time, may argue that strategies such as missile defence now look as flawed as ever - it would have done very little to stop the New York and Washington attacks - the stark exposure of the terrorist threat will give Mr Rumsfeld enhanced power in Washington.

Experience

The defence secretary has years of government and industry experience.

President Bush will be drawing on all of Mr Rumsfeld's experience

The 69-year-old former Princeton University wrestler first became a Congressional assistant in 1957.

After eight years as a congressman for Illinois, Mr Rumsfeld left to work for the Nixon administration in 1969. He served in a range of roles including counsellor to the president.

As secretary of defence under President Gerald Ford, Mr Rumsfeld pushed for increases in the defence budget and dealt with some of the thorniest issues of the Cold War.

After 1976 he worked as chief executive of drug company G D Searle & Company until 1985, and was then chairman and chief executive officer of General Instrument Corporation.

During the 1980s and 90s, Mr Rumsfeld continued to advise Republican administrations and exercise his influence over issues of defence.

'Rogue state' threat

He was the senior adviser to President Reagan's Panel on Strategic Systems in the early 1980s and recently lead an independent commission to review and assess the ballistic missile threat to the US.

It caused a stir when its findings were released in 1998, concluding there was a growing threat from countries like North Korea and Iran, far more serious than the intelligence community had believed.

Mr Rumsfeld's passion for an ambitious missile defence system has continued throughout this year, leading the campaign to persuade a sceptical world of its benefits.

To back him up he has chosen an equally hawkish team of advisers, including his deputy Paul Wolfowitz.

Donald Rumsfeld's Pentagon is at the centre of the new "war" on terrorism, co-ordinating perhaps the most difficult and complicated campaign in its history.