Shaun Walker: Signed in Moscow... the document which divided a continent

Few pieces of paper are as controversial as the one signed in Moscow on 23 August 1939 by Joachim von Ribbentrop and Vyacheslav Molotov. The foreign ministers of Nazi Germany and Soviet Russia put their signatures to a non-aggression pact, as a jovial Joseph Stalin smiled from behind them. A week later, Nazi Germany invaded Poland. In a secret addendum to the treaty, which only became public after the war, the two powers agreed to slice up central and eastern Europe into spheres of influence. The Soviets got the Baltic States and part of Poland, and had invaded the territories by the middle of 1940.

In the West, the pact is seen as the key trigger for war. Countries which subsequently had to endure decades of Soviet or Communist rule have suggested the Soviet invaders were no better than the Nazis, an allegation which infuriates Moscow.

In July, a resolution passed by the Parliamentary Assembly of the OSCE (the Organisation for Security and Co-operation in Europe) equated Stalinism and Nazism, and called for 23 August, the date of the Nazi-Soviet pact, to become a day of remembrance across Europe for the victims of both regimes. The Russian delegation stormed out in fury, and the head of the delegation called it an "insulting anti-Russian attack".

In the past decade, the defeat of Nazi Germany in what Russians still call the Great Patriotic War has been transformed into something of a national idea. Any attempts to portray a more nuanced version of the war years have been met with outrage among Russian officials. The Soviet Union lost millions more troops than any other country, and the line is that the Soviet Union was the unequivocal saviour of Europe. Last year Stalin came third in a poll to name the greatest Russian of all time, and most of his support in contemporary Russia is based on his reputation as a war leader.

Many Western historians have portrayed Stalin as an inept leader in the run-up to the Nazi invasion of the Soviet Union in 1941. It has been suggested he was taken completely by surprise, having refused to believe intelligence passed to him by his generals. Most Russian historians, on the other hand, claim that Stalin was preparing for war all along, and signed the Nazi-Soviet pact simply to gain time to prepare.