With their websites and stickers, their pranks and slogans aimed at banishing widespread fear of a corrupt regime, the democracy guerrillas of the Ukrainian Pora youth movement have already notched up a famous victory - whatever the outcome of the dangerous stand-off in Kiev.

Ukraine, traditionally passive in its politics, has been mobilised by the young democracy activists and will never be the same again.

But while the gains of the orange-bedecked "chestnut revolution" are Ukraine's, the campaign is an American creation, a sophisticated and brilliantly conceived exercise in western branding and mass marketing that, in four countries in four years, has been used to try to salvage rigged elections and topple unsavoury regimes.

Funded and organised by the US government, deploying US consultancies, pollsters, diplomats, the two big American parties and US non-government organisations, the campaign was first used in Europe in Belgrade in 2000 to beat Slobodan Milosevic at the ballot box.

Richard Miles, the US ambassador in Belgrade, played a key role. And by last year, as US ambassador in Tbilisi, he repeated the trick in Georgia, coaching Mikhail Saakashvili in how to bring down Eduard Shevardnadze.

Ten months after the success in Belgrade, the US ambassador in Minsk, Michael Kozak, a veteran of similar operations in central America, notably in Nicaragua, organised a near identical campaign to try to defeat the Belarus hardman, Alexander Lukashenko.

That one failed. "There will be no Kostunica in Belarus," the Belarus president declared, referring to the victory in Belgrade.

But experience gained in Serbia, Georgia and Belarus has been invaluable in plotting to beat the regime of Leonid Kuchma in Kiev.

The operation - engineering democracy through the ballot box and civil disobedience - is now so slick that the methods have matured into a template for winning other people's elections.

In the centre of Belgrade, there is a dingy office staffed by computer-literate youngsters who call themselves the Centre for Non-violent Resistance. If you want to know how to beat a regime that controls the mass media, the judges, the courts, the security apparatus and the voting stations, the young Belgrade activists are for hire.

They emerged from the anti-Milosevic student movement, Otpor, meaning resistance. The catchy, single-word branding is important. In Georgia last year, the parallel student movement was Khmara. In Belarus, it was Zubr. In Ukraine, it is Pora, meaning high time. Otpor also had a potent, simple slogan that appeared everywhere in Serbia in 2000 - the two words "gotov je", meaning "he's finished", a reference to Milosevic. A logo of a black-and-white clenched fist completed the masterful marketing.

In Ukraine, the equivalent is a ticking clock, also signalling that the Kuchma regime's days are numbered.

Stickers, spray paint and websites are the young activists' weapons. Irony and street comedy mocking the regime have been hugely successful in puncturing public fear and enraging the powerful.

Last year, before becoming president in Georgia, the US-educated Mr Saakashvili travelled from Tbilisi to Belgrade to be coached in the techniques of mass defiance. In Belarus, the US embassy organised the dispatch of young opposition leaders to the Baltic, where they met up with Serbs travelling from Belgrade. In Serbia's case, given the hostile environment in Belgrade, the Americans organised the overthrow from neighbouring Hungary - Budapest and Szeged.

In recent weeks, several Serbs travelled to the Ukraine. Indeed, one of the leaders from Belgrade, Aleksandar Maric, was turned away at the border.

The Democratic party's National Democratic Institute, the Republican party's International Republican Institute, the US state department and USAid are the main agencies involved in these grassroots campaigns as well as the Freedom House NGO and billionaire George Soros's open society institute.

US pollsters and professional consultants are hired to organise focus groups and use psephological data to plot strategy.

The usually fractious oppositions have to be united behind a single candidate if there is to be any chance of unseating the regime. That leader is selected on pragmatic and objective grounds, even if he or she is anti-American.

In Serbia, US pollsters Penn, Schoen and Berland Associates discovered that the assassinated pro-western opposition leader, Zoran Djindjic, was reviled at home and had no chance of beating Milosevic fairly in an election. He was persuaded to take a back seat to the anti-western Vojislav Kostunica, who is now Serbian prime minister.

In Belarus, US officials ordered opposition parties to unite behind the dour, elderly trade unionist, Vladimir Goncharik, because he appealed to much of the Lukashenko constituency.

Officially, the US government spent $41m (£21.7m) organising and funding the year-long operation to get rid of Milosevic from October 1999. In Ukraine, the figure is said to be around $14m.

Apart from the student movement and the united opposition, the other key element in the democracy template is what is known as the "parallel vote tabulation", a counter to the election-rigging tricks beloved of disreputable regimes.

There are professional outside election monitors from bodies such as the Organisation for Security and Cooperation in Europe, but the Ukrainian poll, like its predecessors, also featured thousands of local election monitors trained and paid by western groups.

Freedom House and the Democratic party's NDI helped fund and organise the "largest civil regional election monitoring effort" in Ukraine, involving more than 1,000 trained observers. They also organised exit polls. On Sunday night those polls gave Mr Yushchenko an 11-point lead and set the agenda for much of what has followed.

The exit polls are seen as critical because they seize the initiative in the propaganda battle with the regime, invariably appearing first, receiving wide media coverage and putting the onus on the authorities to respond.

The final stage in the US template concerns how to react when the incumbent tries to steal a lost election.

In Belarus, President Lukashenko won, so the response was minimal. In Belgrade, Tbilisi, and now Kiev, where the authorities initially tried to cling to power, the advice was to stay cool but determined and to organise mass displays of civil disobedience, which must remain peaceful but risk provoking the regime into violent suppression.

If the events in Kiev vindicate the US in its strategies for helping other people win elections and take power from anti-democratic regimes, it is certain to try to repeat the exercise elsewhere in the post-Soviet world.

The places to watch are Moldova and the authoritarian countries of central Asia.