Dick Cheney's visit to Kiev today is important - and ironic. The US Vice-President's purpose is to restate American support for Ukraine's democracy and independence in the aftermath of Russia's annexation of South Ossetia. Western leaders justifiably wonder where Moscow might next contemplate the use of force. Ukraine, with eight million Russian citizens and its role for 70 years as engine room of the Soviet economy, is an obvious possibility. Yet military action there is, for now, unlikely, precisely because the Kremlin has no need for it.

Russia's Georgian adventure has been described by the President of Estonia as “a complete paradigm shift in the security architecture of Europe”. Its effects are nowhere more evident than in Ukraine's internal politics. A demand yesterday for the pro-Western Foreign Minister to be sacked for allowing a US warship into Ukrainian waters was dramatic enough, but merely a sideshow for the main event: the collapse of the ruling coalition after the Prime Minister Yuliya Tymoshenko, a charismatic standard-bearer of the Orange Revolution, defected to vote with the country's largest pro-Moscow party to curtail the President's powers.

Mrs Tymoshenko is no friend of Russia. For the past three years she has competed with President Yushchenko for the unofficial title of Ukraine's darling of the West. Yet since Russia's 58th Army burst into South Ossetia a month ago she has been conspicuously reluctant to condemn it. President Yushchenko has accused her of treason for instructing her MPs to switch sides in parliament, but the reality is that she wants his job, and has decided since the invasion of Georgia that to win it she must work with Ukraine's large Russian minority, not against it.

The Kremlin has every reason to be delighted. This year Vladimir Putin privately told Nato representatives in Bucharest that he did not consider Ukraine a real country. Small wonder that the Ukrainian Foreign Minister has claimed since last month that his country is next on Russia's list. Yet as long as Ukraine's most ardent pro-European politicians tack towards Moscow for their own political reasons, the Kremlin has little reason for overt belligerence.

How should the West respond? It cannot do much to influence Ukraine's internal democratic processes; nor should it. If Ukrainian voters back a new alliance of pro-Russian parties in fresh parliamentary elections, that is their choice. A flirtation with Russia might even remind Mrs Tymoshenko and her followers why they have been so eager to escape its clutches for so long.

But there is a serious long-term risk attached - of a resurgent but blinkered Moscow daring eventually to use Ukraine's Russian minority as a pretext for intervention.

Sergei Lavrov, the Russian Foreign Minister, has called the Western fear of further military action by Russia on its former Soviet fringe a “sick fantasy”. The same could have been said of the “liberation” of South Ossetia, yet it happened. Russia has forfeited the trust of the international community and must earn it back. At next week's EU-Ukraine summit in France and at the next Nato summit in December, Western leaders can ill afford to forget this. Ukraine's personalities may come and go, but its hard-won freedoms must stay.