Russian president Vladimir Putin over the weekend celebrated the 70th anniversary of the Soviet defeat of Nazi Germany with a military parade on Red Square and a series of smaller events.

But while standing next to German chancellor Angela Merkel, he appeared to justify the Molotov-Ribbentrop pact which the Soviet Union signed with the Nazi regime in 1939.

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"This pact made sense in terms of guaranteeing the Soviet Union’s security," he said on Sunday (10 May).

Putin noted that Moscow, in the 1930s, had tried to stop Nazi Germany, but felt isolated after Germany, France, and the UK signed the 1938 Munich agreement allowing Hitler to annex parts of Czechoslovakia.

"The Soviet Union made tremendous efforts to put in place conditions for collective resistance to Nazism in Germany and made repeated attempts to create an anti-Nazi bloc in Europe," he said.

"All of these attempts failed. What’s more, after 1938, when the well-known agreement was concluded in Munich, conceding some regions of Czechoslovakia, some politicians thought that war was inevitable," he added.

"When the Soviet Union realised that it was left to face Hitler’s Germany on its own, it acted to try to avoid a direct confrontation, and this resulted in signing the Molotov-Ribbentrop Pact".

The Molotov-Ribbentrop accord was signed on 23 August 1939.

Three days later, the German army was mobilised and nine days later Hitler attacked Poland, triggering declarations of war by France and Britain.

Many historians believe the Molotov-Ribbentrop deal allowed Hitler to start the war because he knew he wouldn’t have to face the Soviet Union.

But the Soviet Union was itself invaded in June 1941, when Hitler launched a surprise attack.

Speaking after Putin, Merkel noted that besides being a non-aggression pact, the the Molotov-Ribbentrop accord was also an agreement to dismantle Poland.

"From my point of view, the Molotov-Ribbentrop Pact is hard to understand unless you take into consideration the extra secret protocol," she said, implying Putin gave an inaccurate assessment of the accord.

“From this point of view, I consider it was not right, it was done on an unlawful basis."

Stalin attacked Poland on 17 September 1939, in accordance with the Molotov-Ribbentrop deal, on the pretext that he had to protect Ukrainian and Belarussian minorities.

Merkel, and most EU leaders, boycotted the Red Square military parade on Saturday (9 May) in protest at Russia’s involvement in the war in Ukraine.

But she attended a wreath-laying ceremony at the grave of the Unknown Soldier with Putin on Sunday.

"Because of us [Germans], millions of people died and the Red Army played a decisive role in the liberation of Berlin," she said.

"We have learned from bitter experiences, difficult situations, and now we have to overcome one by peaceful and diplomatic means," she added, referring to the Ukraine crisis.

The chancellor said she regretted that "we still do not have a ceasefire" in eastern Ukraine, despite the "Minsk" ceasefire agreement, but underlined that "we work with Russia, not against her".

For his part, Putin admitted both leaders "differ considerably in [their] assessment of the events that led to the anti-constitutional coup in the Ukrainian capital in February 2014”. But he adopted a conciliatory tone.

"We will exert all possible influence on the authorities in Donetsk and Lugansk [in occupied east Ukraine] in order to ensure that this process goes at the hoped-for speed and quality. Ms Merkel and I agreed to work more closely on the crisis in Ukraine, including through the Normandy format," he said, referring to talks between Ukraine, Russia, Germany, and France.

Meanwhile, European Council president Donald Tusk compared "the evil" of World War II with the current war in Ukraine.

"We have read that evil is banal – [Ukrainian] president Petro Poroshenko knows better than we do today that evil is here again," he said on Saturday (8 May) at a war memorial in Gdansk, in his native Poland.

"I believe that Europe can be responsible in a different way than in 1939, that Europeans can feel responsible for the entire continent, not just for their [own] people," he said.

"We've started to wonder which victory the organiser of the parade has designated for the future," Tusk added, on Putin’s 9 May parade.