For years now, the criticism that the West is trying to "revise" the history of World War II has been a steady mantra from supporters of Russian President Vladimir Putin.

And many in the West do not fully appreciate the enormous sacrifices of the Soviet people -- who lost an estimated 20 million lives -- to the defeat of Adolf Hitler's Germany.

But on May 1, during a clutch with journalists in the Belarusian city of Brest, it was the turn of Aleksandr Zaldostanov, the leader of the notorious pro-Putin Night Wolves motorcycle club, to indulge in some significant historical revisionism.

A reporter from the independent Belsat asked Zaldostanov to comment on the fact that in the early days of the war, Stalin's Soviet Union and Hitler's Germany were allies.

"The U.S.S.R. sided with Hitler!" Zaldostanov replied in astonishment. "You see how messed up this guy is. Here is a clear example of the mess in some people's heads. The U.S.S.R. sided with Hitler, he's telling me. Either he is insane or he's trolling. What else can I say?"

A few seconds later, he pushed the persistent reporter aside and moved on to the next question.

Ironically, the incident happened in the city of Brest, which in 1939 was in Poland -- and formed part of the border between the Soviet Union and Nazi Germany that was agreed as part of the secret protocol to the infamous Molotov-Ribbentrop Pact. Nazi Germany invaded Poland from the West on September 1, 1939, and the Soviet Union invaded from the east on September 17.

Nazi-Soviet Parade

Just a few days later, Poland was all but finished militarily, and the two invading armies held a joint military parade in Brest on September 22, 1939, in a dark parallel to the more famous meeting toward the end of the war of Soviet and American troops on Germany's Elbe River on April 25, 1945.

The joint parade was just the most visible moment in a long period of military and economic cooperation between Germany and the Soviet Union that stretched back to the 1920s and only ended with the Nazi invasion of the Soviet Union on June 21, 1941.

WATCH: Soviet And German Soldiers March Together In Brest

Both countries were aggrieved by the peace settlements that ended World War I and sought to undermine them.

According to British historian John Erickson in his 2001 book The Soviet High Command, Soviet diplomats approached their German counterparts about partitioning Poland several times in the 1920s.

Although Germany was forbidden by the Versailles Treaty from having an air force, the Junkers firm created a factory outside Moscow and Luftwaffe pilots trained near Lipetsk. The Germans practiced the blitzkrieg at a tank school in Kazan and produced banned chemical weapons in Samara Oblast. German submarines hid from Versailles inspectors at a base near Murmansk.

However, Stalin's most fateful involvement in Germany in the 1920s was political. He stubbornly banned the Soviet-controlled Communist Party of Germany from cooperating in any way with the leftist Social-Democratic Party, a policy that helped pave the way for Hitler.

Relations slowed considerably after Hitler's rise to power, mostly because of Hitler's avowed anticommunism and anti-Slavic racism. The 1930s were a difficult time in European international relations, with all countries struggling to boost their security in a growing atmosphere of mutual mistrust. Numerous bids at various collective-security arrangements failed, as did the West's de facto policy of appeasing Hitler.

'Planting Ideas'

In the summer of 1939, Stalin entered into talks with Germany that resulted in the Molotov-Ribbentrop Pact in August of that year. This was accompanied at almost the same time by the German-Soviet Commercial Agreement, under which the Soviet Union agreed to provide massive amounts of raw materials to Hitler's regime.

Under the secret protocols to the nonaggression pact, the two countries agreed to divide up Central Europe, with the Soviet Union taking eastern Poland, the three Baltic states, and the Romanian region of Bessarabia. Until the 1990s, the Soviet (and, later, Russian) government denied the very existence of the secret Molotov-Ribbentrop protocols.

One week after the signing, Hitler invaded Poland. Two weeks later, the Soviet Union followed suit. In late September and early October, the Soviet Union occupied the Baltic states. In October 1940, Germany and the Soviet Union briefly negotiated a draft treaty under which the Soviet Union would join Germany, Japan, and Italy as an Axis power. By that time, however, Hitler had already made up his mind to invade the Soviet Union, so those talks came to nothing.

The biker Zaldostanov's ignorance -- feigned or not -- of the Soviet Union's cooperation with Hitler's Germany and their joint invasion of Poland in 1939 found a more alarming echo last week in a comment by Russian General Aleksandr Kirilin, an aide to Defense Minister Sergei Shoigu, on Russian radio.

Criticizing the Polish government's policies on Soviet war memorials, Kirilin said "it is not appropriate for a European state that was occupied by Nazi Germany and could not get rid of the Nazi occupation if not for the Soviet Union's help."

"Attempts are being made to plant the idea in our minds that we invaded them," he concluded.