By Paul Reynolds
World Affairs correspondent, BBC News website
The presidential election result in Ukraine is another striking example of the "people power" which has swept central and eastern Europe over the last 15 years.
The "Orange Revolution" will take its place alongside the "Velvet Revolution" in former Czechoslovakia, the "Rose Revolution" in Georgia and all the other revolutions which might not have a name but which certainly had an effect.
The strength of Ukraine's people power surprised many in the West
These peaceful revolutions have transformed the political landscape of Europe. And just as the changes in other countries led to questions about EU and Nato membership, so the election of Viktor Yushchenko will inevitably do so in Ukraine.
The European Union is likely to have to re-examine its rather hands-off attitude to potential Ukrainian membership.
The EU will not want to engage in triumphalism against Russia, whose President Vladimir Putin openly backed Viktor Yanukovych in the first, disputed election.
But the boundaries of modern Europe have now been pushed further east, and Russia itself is finding that its immediate western neighbours have diverged from the authoritarian path it has trod under Mr Putin. The long-term effect on potential liberalisation in Russia itself will be interesting to watch.
There will be voices in the EU calling for swift action to consolidate Ukraine's new position, which will be far more open to western ideas of political and economic reform.
Ukraine is likely to withdraw its 1,600-strong contingent from Iraq
When he was appointed prime minister by President Leonid Kuchma in 1999, Mr Yushchenko, who once headed Ukraine's national bank, initiated a series of economic reforms.
These measures ran up against entrenched interests, led by a combination of communists and Ukraine's oligarchs who had done well out of post-communist rule. He lost office in 2001, but those same policies can now be expected to make a return appearance.
At the moment, Ukraine has a partnership agreement with the EU and is regarded as one of the countries to be fostered under the so-called European Neighbourhood Policy, which is designed to extend friendship but not membership.
The partnership agreement does foresee the development of free trade in exchange for political reforms, but this process might now not only be speeded up but superseded altogether.
Ukrainian membership of the EU could well be on the agenda before too long.
In an article on 7 December for Open Democracy, an online political magazine, Katinka Barysch and Charles Grant of the Centre for European Reform argued: "The EU should, and probably will, rethink its long-standing position that Ukraine 'has as much reason to be in the EU as New Zealand', in the words of Romano Prodi, the recently departed European Commission president".
The authors did counsel against the EU "making a big noise about Ukraine becoming an EU member". But experience elsewhere in eastern Europe has been that a rapid change in a country's internal politics is usually followed by a rapid change in its external relations.
Ukraine's ageing Soviet-era hardware is incompatible with Nato's
There might not be a big noise, but some noise can be expected.
As for Nato, it already has a partnership agreement with Ukraine, though Ukraine has never walked through the open door to membership that Nato has offered. That, too, might change, though Mr Yushchenko's need to keep strong relations with Russia and his own nationalist sentiments could act against it.
No US puppet
Mr Yushchenko is unlikely to be a client of the West, especially not of the United States, despite claims from those opposing him that his Ukrainian-American wife Kateryna wields great influence. A significant neo-conservative figure in her day, she held office in the human rights bureau at the US State Department in the Reagan administration.
Mr Yushchenko has supported a withdrawal of Ukrainian troops from Iraq and its 1,600-strong force there could be brought home, though probably not before the Iraq election on 30 January.
The real winners are those Ukrainians who use the same words and phrases as one heard in the other peaceful revolutions - words like "truth", "rule of law," decency" and "normality."
The previous regime epitomised the rule of those who had not quite thrown off the old ways of doing things. They claimed to have changed, but underneath it was not that different.
One symbolic moment for me came when I accompanied the Prince of Wales on a visit to Ukraine in 1996. He had just arrived for a lavish dinner in some state palace in Kiev when all the lights failed.
They had to drive a Mercedes up to the front door to shine its headlights into the room.