Mary Dejevsky: It's time to purge the long and painful legacy of Katyn

The Russian government has just embarked on its latest attempt to improve its image. Its first fumbling efforts began in 2004, when then President Putin realised how negatively both he and Russia were regarded abroad. Two years later, Russia appointed the American PR agency, Ketchum. Now a home-grown commission has been created, answerable directly to President Medvedev, who is said to be unhappy – as well he might be – with how Russia was cast as the villain in the war with Georgia.

National image, though, is not something easily changed – not in a positive direction, at least. And there is more bad news heading Russia's way, with the international release of Katyn, an authoritative and affecting film about the massacre of Polish officers in a Russian forest in 1940. It is the work of the eminent Polish director, Andrzej Wajda, whose father was among those who died.

In many ways, the film is a hymn to Poland's officer class, for whom homeland and honour took precedence even over family. Depicting the military elite as the product, even the highest expression, of Poland's pre-war middle class, it also immortalises a bourgeois way of life that was mostly hidden once the iron curtain had descended. It reminds today's Polish middle class of the tradition to which they belong.

Even more, though, Katyn is a study in truth and consequences. As such, it could not have been made in Poland even as recently as 1989. For Katyn – the word massacre is understood – was a taboo subject in post-war Poland, unless you accepted the officially-ordained lie that the killers were not Russian, but German. As one character says, ignorant of the double meaning obvious to the audience: "Your attitude to Katyn reflects your attitude to Poland."

By shifting the official date of the killings by a year, Soviet propagandists incriminated the Germans who had by then occupied Western Russia, and co-opted Katyn into the USSR's patriotic anti-Nazi myth-making. Poles had to accept a false date and false perpetrators for an atrocity that annihilated their brightest and best, or hold their peace.

It was only when the Soviet bloc unravelled that Poles could speak the truth without risk of persecution. In the meantime, two generations had grown up with the presumption that all officials lied and that they had to be party to those lies to qualify for advancement. Wajda's film represents a national catharsis.

It would be heartening to believe that Katyn will be seen as being less about wicked Russians than about the truth. And Wajda's narrative, while featuring mostly upright Poles, allows that not all were high-minded. Just as the "good" German is a cliché of British war films, so Wajda also provides a "good" Russian.

It is possible, too, that Poles who have grown up since the end of the Cold War will identify with Katyn less than their elders. Internet message boards suggest that younger Poles – as cynical, perhaps, as their British counterparts – are impatient with set-piece glorification of a past social order. Their comments are more critical than you might imagine.

All that said, however, Katyn is unlikely to do a great deal either for Russia's international image or for Polish-Russian relations. And it is, in a way, tragically predictable that the film's release comes just as post-war tensions seemed finally to be in easing and a more normal relationship seemed in prospect.

National image is a complex phenomenon, made up not only of first-hand experience, but inherited memory and expectations. Nor can it be completely controlled by national governments. The real Kazakhstan had to contend, out of the blue, with the fictitious Borat, while the highly negative image of the US in Bush's second term was reversed, literally overnight, by the election of Barack Obama.

But Russia is not powerless to limit the damage from Katyn. Although the late Boris Yeltsin, acknowledged the truth, as have several commissions of investigation, the Kremlin's public stance remains ambiguous. Even now, some Russian publications treat Katyn as a German atrocity, or something unresolved. Medvedev could rectify that: an official ceremony at Katyn, a formal acceptance of responsibility, even perhaps an invitation to Wajda to present his film in Russia. It would not change everything at a stroke, but it would be a modest start to a new, and more truthful, age.

independent.co.uk/mary-dejevsky

m.dejevsky@independent.co.uk