CIVIL strife often follows a grimly predictable pattern. What at first seems a soluble dispute hardens into conflict, as goals become more radical, bitterness accumulates and the chance to broker a compromise is lost. Such has been the awful trajectory of Ukraine, where protests that began peacefully in November have combusted in grotesque violence. The centre of Kiev, one of Europe’s great capital cities, this week became a choking war zone. Buildings and barricades were incinerated and dozens of Ukrainians were killed. Despite talk of a truce between some of the participants, the horror could yet get much worse. The bloodshed will deepen the rifts in what has always been a fragile, complex country (see article). Outright civil war remains a realistic prospect. Immediate responsibility for this mayhem lies with Viktor Yanukovych, Ukraine’s thuggish president. But its ultimate architect sits in the Kremlin: Vladimir Putin.

Neither East nor West

The territory that is now Ukraine has a long and painful history as a bloody borderland between East and West. But it came into being as an independent nation only in 1991, when the Soviet Union collapsed. Combining lands in the west that had once been part of Austria-Hungary, and a Russian-speaking south and east, the new country always had its doubters. Since then Ukraine’s politics have been characterised by infighting and graft—including in the years following the orange revolution of 2004, a peaceful uprising whose promise was squandered by its rancorous leaders. Many Ukrainians feel their state has been captured by a corrupt elite, which cannot be dislodged by the usual democratic means. Kiev is one of the few European cities where the European Union is synonymous with good government and the rule of law.

It was Mr Yanukovych’s rejection, in November, of a trade agreement with the EU, in favour of an opaque deal with Russia, which started the unrest. Soon the protesters were demanding his resignation, while Mr Yanukovych and Russian propaganda denounced them as terrorists. How, after three months of tetchy stand-off, the killing started this week is murky. But most of it was perpetrated by the president’s men.

The response from the West should be firm. The president’s henchmen deserve the visa bans and asset freezes that America has imposed and the EU is considering. Mr Yanukovych must rein in his troops and, if he can, the plainclothes goons who are committing much of the violence. But the protesters, if they want to stop a full-scale blood-bath, also need to compromise—to quit their symbolic base in Kiev’s Independence Square, and the other buildings they have occupied. The best option would be for the two sides to form a transitional coalition government.

A presidential election is due in 2015: it should happen this year instead, preferably without Mr Yanukovych. His regime has featured rampant cronyism, the persecution of his rivals, suborning of the media and nobbling of the courts, now topped off by slaughter. But he will be hard to move. Built like a bouncer, he twists like a weasel; he is likely to try to wriggle out of any commitments he makes when he thinks the crisis has passed. If so, the tycoons who have sustained his power, and who have much to lose in this madness, must force him out.

What should come next is less clear. Virtually all of Ukraine’s established politicians have discredited themselves, including Yulia Tymoshenko, the jailed opposition leader. The protesters have no clear champion—one reason the violence may prove difficult to stop. It is hard to envisage a candidate emerging who will bridge the underlying fault-lines in Ukrainian society (see map). Mr Yanukovych still commands support in the east and south; in Kiev and the west, where protesters have seized government facilities, he is reviled. A split remains terrifyingly plausible. Avoiding that fate requires, above all, an end to the Russian meddling. Mr Putin may not have lit the match this week, but he assembled the pyre. To most rational observers, fomenting chaos across the border in Ukraine might seem an odd ambition for Russia. Not to Mr Putin, who regards Ukraine as an integral part of Russia’s sphere of influence, and saw the orange revolution as a Western plot to steal it. His economic sanctions and threats helped to persuade Mr Yanukovych to turn his back on the EU. It is clear that the loans and cheap Russian gas that prop up Ukraine’s teetering economy are conditional on Mr Yanukovych taking a tough line with the protesters. Mr Putin’s bullying and machinations have brought Ukraine to this pass. If Mr Yanukovych clings on, weakened at home and ostracised abroad, Mr Putin will be content, for he will have another dependent leader to add to his collection of pliable clients. But he might not stop there. Russian hawks have long wanted to annex Crimea, a Black Sea peninsula that Nikita Khrushchev transferred to Ukraine (reputedly while drunk). This upheaval could provide a pretext for Mr Putin to grab it. Either way, a wretched Ukraine will help convince his people that street protests, and political competition, are the road to ruin.

Confronting the Kremlin

It is past time for the West to stand up to this gangsterism. Confronting a country that has the spoiling power of a seat on the UN Security Council, huge hydrocarbon reserves and lots of nuclear weapons, is difficult, but it has to be done. At a minimum, the diplomatic pretence that Russia is a law-abiding democracy should end. It should be ejected from the G8. Above all, the West must stand united in telling Mr Putin that Ukraine, and the other former Soviet countries that he regards as wayward parts of his patrimony, are sovereign nations.

There is a kind of rough justice in the timing of Ukraine’s turmoil. In 2008 Russia invaded Georgia, its tiny southern neighbour, just as the Olympic games began in Beijing, prompting formulaic Western protests but no meaningful retribution. The events in Kiev interrupted the winter Olympics in Sochi, intended to be a two-week carnival of Putinism. This time the West must make Mr Putin see that, with this havoc at the heart of Europe, he has gone too far.