Vladimir Putin has won plaudits at home and brushed aside censure abroad with his brazen theft of Crimea. His few supporters at the UN last week tellingly included some of the planet's most unsavoury regimes, such as North Korea, Syria, Sudan and Zimbabwe. Their leaders no doubt appreciated the skilful blend of force, speed and propaganda with which he seized the region from Ukraine.

But it is extraordinary that the Russian president has bedazzled so many in the west – and not just his new admirer Nigel Farage. Putin is the autocratic leader of a regime reviled for domestic repression and systemic human rights abuses. He is a man accused of overseeing atrocities in his quest to restore the Russian hegemony destroyed by the collapse of the Soviet Union – something he outlined quite openly in his first speech to the Duma.

Yet many people fell for his farcical referendum, held at gunpoint and boycotted by big chunks of Crimea's population. They ignored polling showing that only a minority supported joining Russia – as well as the paltry 4% support won by the party that advocates Russian unity and now runs the region.

Even before I left last week after a month there, some Russian speakers were regretting their support as economic and social realities have hit home; other Crimeans have simply fled.

Now Putin, with his tanks and troops lined up on the border, has gone further. His foreign minister, Sergei Lavrov, insists that Ukraine is effectively dismembered. The country cannot function as a unified state, he says, and must become a loose federation with autonomous powers given to regions bordering Russia. He adds that Ukraine is not permitted to join Nato – which is, remember, a self-defence alliance.

Pause for a second. Imagine the furore if France, for example, demanded the break-up of Switzerland to protect French speakers, with the creation of a crippled client state on its borders. Yet Putin behaves like a 19th-century imperial overlord, still playing the great game as his country resorts to blackmail, while too many observers fall for the lie that Russia has a unique historic right to dictate events in neighbouring nations.

The Soviet Union crumbled because it was an economic, moral and political disaster; many citizens could not wait to throw off the chains of communism imposed from Moscow. Now Putin seeks to extend the Russian empire once again – and with it the reach of his brutal and venal rule. And he does so because he feels threatened by the potential outbreak of liberal democracy in Kiev following the overthrow of his patsy president, fearing that ripples may spread elsewhere around his backyard.

So Putin's propaganda machine promulgates the idea that Ukraine has been taken over in a coup by a bunch of Nazis. But, as Yale historian Timothy Snyder points out, the restoration of democracy could not be further from fascism. Polling for May's presidential election indicates that the highest-placed far-right candidate is on course to get a lower share of the vote than the BNP won in the last British general election.

Western criticism has been weakened by misguided interventions in Afghanistan and Iraq – and, indeed, by a short-sighted failure to stop flows of illegal cash so corrosive to countries such as Russia and Ukraine. But this should not prevent firm support for the fledgling democracy in Kiev, with financial help, military training and tougher sanctions on Putin, his banks and his circle if they remain belligerent.

Instead, there seems to be too much tacit acceptance of the annexation of Crimea, which will have been noted in the Kremlin, and too little thought given to Ukrainian self-determination.

Putin's refusal to play by conventional global rules should shake any complacency, as it raises profound questions. One leading Eurosceptic told me he now thought the continent needed a combined army, while a harsh critic of the Iraq conflict praised President Obama's tough stance. But above all there must be clarity over who is the bad guy in this new cold war drama as he seeks to extend his Russian empire.