Things weren't easy in Ukraine when I lived there in the early 1990s, just after the country voted to break from Moscow. There was hyperinflation. People lost their savings. There were petrol shortages. The airport in Kiev would close for days at a time for lack of fuel. Nothing got repaired; nothing got built.

But nobody starved. Nobody froze. The electricity was never cut off. The trains kept running, schools and hospitals limped from day to day. Most importantly, horrifying as it was for Ukrainians to watch on the television news how long-peaceful places they knew, such as Georgia, Moldova and Chechnya, were suddenly on fire with heavily armed men strutting across them, they were far away.

There was much grumbling about the Ukrainian government, its incompetence, its corruption. There always seemed the possibility, in the abstract, that Russia might try to come back. In the mid-1990s I wrote an article for the Guardian suggesting a scenario for a new Yugoslavia in the east, with Ukraine as Croatia, Crimea as Bosnia and Russia as Serbia. But I felt I'd pushed it. After all, Boris Yeltsin was no Milosevic.

I remember visiting Ukraine one springtime in the mid-1990s. Days earlier, in Chechnya, I'd seen shell-ruined buildings, terrified civilians, battle-hardened separatists and frightened Russian conscripts. In Ukraine I drove past Ukrainian soldiers gathered around a radar truck; each one was blissfully asleep, bathed in the soft May sunshine. It made me smile. After all, what did they have to worry about? Ukraine had given away its nuclear weapons and in return, the country's territorial integrity was guaranteed in a document signed by Russia, the US and Britain.

And then Russia got its Milosevic. Like his Serbian counterpart, Vladimir Putin is clever, articulate, popular, untrustworthy to those who are not his friends, ruthless, cynical to the point of absurdity and unable to account for his personal wealth. Like Milosevic, he has no compunction in exploiting the messianic, victim-narrative strain of his country's patriotism. Unlike Milosevic, because of Russia's nuclear arsenal, he is invulnerable to military attack from outside. Unlike Milosevic, he has had many years of income from raw materials exports with which to build up powerful, well-equipped security forces to carry out a well-targeted upgrade of Russia's military, to turn the media into a government mouthpiece, to repress or buy off dissenters, and to offer the outside world the convincing illusion that his country is prospering. (It is true that Russian pensioners are somewhat less miserably poor than those in Ukraine.)

Now, a generation later, long after it had been unthinkable, those same chaotic figures with Kalashnikovs and fatigues have appeared in Ukraine, under Russian sponsorship and, all evidence suggests, direction.

First came the direct Russian military takeover of Crimea. The weekend saw an apparent attempt by proxy to separate the eastern regions of Donetsk, Luhansk and Kharkiv, and perhaps others, from Kiev's control.

There are multiple possible interpretations of what is unfolding in eastern Ukraine. The Putinite "men in green", as they are now being called by Ukrainians, for the time being have the active support of some locals, particularly pensioners. But one essential point is beyond dispute. Nothing that has happened in Ukraine up to now justifies either military intervention by Russia or the injection of armed mercenaries and irregulars into a peaceful country.

In the wake of the revolution in Kiev that drove the corrupt president Victor Yanukovych to flee, Ukraine faced a world of problems. Not one of those problems has been made easier by Putin seizing Crimea or sponsoring insurrection in eastern Ukraine. Ever since the revolution, Putin has promoted the idea that Ukraine is in "chaos". But there was no chaos, so he made some. The only chaos in Ukraine has been caused by Russian intervention.

Putin has promoted the notion that ethnic Russians were in danger. There has never been evidence for this unless you count as brutal repression a failed attempt to revive an old law making Ukrainian the sole language for court hearings and government forms. Putin calls for greater autonomy for the south and east of Ukraine, and more rights for Russian-speakers, while doing all he can to obstruct elections that would bring them back into the political process.

A dangerous line was crossed today when a Ukrainian security service officer was killed by one of the "men in green" at a roadblock set up by the Russian proxies near Slavyansk – the first time since Putin invaded Crimea that blood has been shed during an attempt by Ukrainian government forces to assert control.

Putin has put Ukraine's weak transitional government in an impossible position: fail to resist and I will invade. Resist and I will invade more, and there will be corpses. Although they would never admit it, the authorities in Kiev are resigned to the loss of Crimea. But they don't know where or when Putin will stop. His strategy has blighted the future of Ukraine's 46 million people, making it impossible for any part of the country to move forward.

Hearing the opinions of people in Britain, Europe and America since Russia began to dismember Ukraine, I've been struck by how disagreement tends to focus on which of the two sides has behaved worst: Putin or the west. The complexities of the people of Ukraine tend to vanish in this binary view, alarmingly close to the Putinite consensus, which is that if you live in Ukraine you must either be a loyal vassal to Russia or a fascist.

The truth is that between the minority of archaic radical nationalists in Ukraine's far west, whose role in the revolution won them a few posts in Kiev's otherwise moderate government, and the minority of neo-Soviet extremists in the east, there is a larger group of Ukrainians for whom the difference between the two cultures and languages is trivial. What they want is for their country to be an east Slav space that is fairer and less corrupt than either Putin's Russia, Yanukovych's Ukraine or Lukashenko's Belarus. Whichever way Europe and the US act, it must be with the interests of that group in mind.

In a haunting article, written during Putin's invasion of Crimea, the Ukrainian writer and ethnic Russian Yelena Styazhkina said: "Ukraine is my motherland. The Russian language is my native language. Let Pushkin save me and liberate me from sadness and anxiety. Pushkin, but not Putin."