Belarus is a riddle. How has an Eastern European country the size of England and Wales managed to preserve a Soviet-style dictatorship and a thinly disguised command economy for 17 years while each of its four western neighbours has undergone a revolution or rapid economic transformation — or both?

The answers are not heartening, but neither are they complicated. The first involves the country’s eastern neighbour, Russia. Its attitude to its former Soviet “partners” has evolved over the past decade from Boris Yeltsin’s reckless abandon to Vladimir Putin’s readiness to back a pariah regime in Minsk rather than risk letting Belarus follow Georgia, Ukraine and Kyrgyzstan out of what the Kremlin persists in calling its sphere of influence.

The second explanation for Belarus’s survival in socialist aspic is the success, politically at least, of crude redistributive policies that have bought its leader a measure of grudging loyalty among pensioners and the underemployed. The third explanation is that this leader, Alexander Lukashenko, is a successful thug.

In his 12 years in power, Mr Lukashenko, an ice hockey fanatic and former collective farm manager, has dissolved parliament, replaced it with handpicked loyalists, named himself the nation’s father-figure for life and rewritten the Constitution to let him stand for re-election as President for a third time on March 19. He has also allowed his secret police, still called the KGB, to arrange the disappearances of dozens of critics and opposition figures. Last week his chief rival in the election, Alexander Kozulin, was arrested outside his own headquarters, detained for eight hours and badly beaten by police.

The unreconstructed brutality of Mr Lukashenko’s regime will determine the result of the forthcoming poll. It should also determine the wider world’s response. “There is not enough outrage and international attention on Belarus,” Stephen Hadley, the US National Security Adviser, said after a bruised Mr Kozulin returned to work. The remark was accurate, but outrage alone will not be enough. Britain must lead, not follow, in denouncing electoral fraud, listening sympathetically to Belarussian political asylum-seekers (as the United States has already) and, if necessary, threatening diplomatic sanctions.

Realpolitik demands that Britain, like most of Europe, maintain a working relationship with Russia because of its commanding position as an energy supplier. But the West has little to lose by condemning Mr Lukashenko for the deluded despot that he is, not least because Mr Putin has little to gain by defending him.

Belarus, ruled variously by Poland, Lithuania and Russia until 1991, has little experience of independent nationhood. But Mr Lukashenko’s approach is no way to build a nation. Should he declare himself its re-elected leader, as expected, the international community must leave him in no doubt that it is not fooled by this “result”, or that its backing for his brave and growing opposition is real and unflinching.