History has become a weapon in Russia's battle with the West over Ukraine as President Vladimir Putin looks increasingly to the past to whip up patriotism and rally support. Last month's lavish commemorations of the defeat of Nazi Germany in World War Two, several declarations by Putin and new history textbooks have all presented what some independent historians say are slanted or rewritten versions of the past. The Nazi-Soviet pact that divided Poland in 1939 - which saw Moscow seize much of what is now Ukraine, Belarus and the Baltic States - is now seen in a positive light. A new justification has been found for the Soviet-led invasion of Czechoslovakia in 1968 and some of Soviet dictator Josef Stalin's worst crimes have been played down. "It is an aggressive stance in the debate over history," said Alexei Miller, a history Professor at European University in St Petersburg, who says all sides have been distorting the past during the conflict. "History is a victim of the current crisis in relations between Russia and Europe." He says "wars of memory" are being waged with the West and ex-Soviet neighbors such as the Baltic states and Ukraine, where history is increasingly being interpreted in different ways to suit political views. Putin, who denies Western accusations of sending troops and weapons to pro-Russian separatists in eastern Ukraine, has made clear that he understands the power of history.

State media are an important weapon in Russia's information war with Ukraine and the West, which imposed economic sanctions on Russia after it annexed the Crimea peninsula from Ukraine last year. They are also part of the battle over the past. Rossiya-1 television aired a documentary on May 23 which gave a new explanation for the 1968 invasion of Czechoslovakia, then part of the Soviet bloc, by Communist Warsaw Pact armies which crushed the Prague Spring, intended to create "socialism with a human face". Citing what it called newly discovered documents, it said the invasion was needed to protect the country against a NATO-backed coup being planned under the cover of the Prague Spring. Czech and Slovak officials said the program distorted the facts. Slovakia's Foreign Ministry said Slovaks "refute all attempts at rewriting history". During the crisis in Ukraine, Moscow has portrayed ethnic Russians or Russian speakers living in the former Soviet republic as threatened by fascists.

Russia has now introduced a law which criminalizes the "rehabilitation of Nazism" and makes it punishable by up to three years in prison. The law attracted attention when investigators opened a case against a 16-year-old for posting comments on social media they said praised Nazi Germany's invasion of Poland in 1939. Authorities have also used the law to open criminal cases against defacers of Soviet monuments, including in Ukraine. Unlike similar laws in other countries, Russia's also criminalizes "knowingly spreading false information about the activities of the USSR in World War Two". The Baltic States and Ukraine have also passed laws about history. Ukraine has banned Communist symbols and made it a criminal offence to deny the totalitarian nature of Soviet rule from 1917 to 1991 or to question the legitimacy of anti-Soviet nationalist groups which at times cooperated with the Nazis.