For a country with the biggest marketing industry on earth, the US has made a surprisingly poor job of managing its own image - a problem that has shifted sharply into focus in the propaganda war that has broken out since the September 11th attacks.

It is true that, for much of the world, the US stands as a beacon of freedom. But even outside the ranks of the al-Qaeda terrorist organisation and the US's other enemies in the Middle East, it is sometimes loathed by detractors who accuse it of spreading a culture of crass commercialisation around the world.

And so the question arises: is it time to rebrand the US?

The Bush administration seems to think so. Last month, a new under-secretary of state for public diplomacy and public affairs was sworn in, charged with winning the hearts and minds of the world in the anti-terrorist war. The chosen candidate was not some career diplomat or politician but Ms Charlotte Beers, previously chairwoman of the J. Walter Thompson (JWT) advertising agency.

Variously known as the queen of Madison Avenue and the most powerful woman in advertising, Ms Beers (66) has devoted her working life to the idea of building and selling brands.

Born in Texas to an oilman father, Ms Beers developed a "steel magnolia syndrome" - a lethal combination of irresistible charm and indomitable will.

After graduating with a degree in maths and physics, she became a brand manager for Uncle Ben's Rice, doing multiple regression analysis. She went into the advertising industry after Uncle Ben's hired JWT.

"In walks this eclectic crowd of interesting people and I thought, 'Those people are having more fun than I am'," she remembers. Two years later she was one of them.

She left JWT after 10 years to become boss of the smaller Tatham-Laird & Kudner. She helped merge that agency with France's RSCG and then planned a career break. But she could not resist the top job at Ogilvy & Mather. She retired in 1997 but re-emerged two years later to chair JWT.

In her new job, her narrowly defined priority will be to win the propaganda war against the terrorists and their supporters. But in effect, her role is much broader. It means using the techniques she has learnt in advertising to sell the US, its values and foreign policy to the rest of the world - possibly the biggest brand assignment in history.

It is not just a large task but also an extremely difficult one. People have had various stabs at rebranding countries in the past but it has been a hit-and-miss affair.

Brand experts say it is easier to rebrand a small country than a large one because people in the rest of the world are likely to have fewer preconceptions.

The US, however, is at the opposite end of the spectrum.

"The US is outstanding in the sense that it is the only country in the world which is so well known that you can guarantee people from all other countries will have a view on it," says Mr Wally Olins, co-founder of the Wolff Olins brand consultancy, who has worked on many projects to rebrand countries.

Oddly, Mr Olins adds, people's views can be extremely muddled. They may include contempt for the shallow materialism of US consumer culture, admiration for the values the nation upholds and wonder at its scientific and technological sophistication.

In a sense, there are at least two US cultures: the culture of its noble ideals such as democracy and respect for individual rights; and the pervasive popular and commercial culture represented by Hollywood and MTV.

While a lot of people admire and desire the former, some are much less enthusiastic about the latter. And they are especially resentful when they feel their cultures and traditions are threatened by the incursion of tawdry but seductive US consumerism.

Steve Hayden, vice-chairman of Ogilvy & Mather, says part of the US's image problem is that, as US pop culture and brands have expanded globally, they have increasingly dominated people's perceptions of the US.

"If you can't burn down the American embassy, you can burn down the movie theatre where an American film is playing; if you can't get to the air base, you can attack a McDonald's," Mr Hayden says.

As ever, it is easier to diagnose the problem than to find a solution. Addressing the Senate committee on international relations last month, Ms Beers seemed low on radical ideas: some tweaking of the State Department's website and a beefed-up exchange programme for foreign journalists were among her suggestions.

Mr Olins says people's preconceptions of the US are so deeply entrenched that they will be hard to budge. The way to do it, he says, is to influence the influencers.

"You have to talk to all the people who are making an impression of America in the outside world and attempt to persuade them that the impressions they make have to be in some way coherent and cogent and favourable."

The US has been some way down this road before. In 1942, after the bombing of Pearl Harbor, the US advertising industry founded a body called the War Advertising Council, which made commercials reminding people that "loose lips sink ships" and recruiting women into the workforce with the "Rosie the riveter" symbol.

That organisation, now called the Ad Council, still exists. Ms Beers told the Senate committee she had spoken to it about sponsoring commercials in the US and overseas that would "distil the values and virtues of American democracy". One such commercial, I Am An American, is already showing in the US.

Ultimately, advertising executives and brand experts agree that nations are judged by what they are and what they do, not by how they would like to be seen.

But propaganda can be a powerful weapon in times of war and, if advertisers are to help the campaign, Ms Beers may be the person to do it.