Victory Day, one of Russia's most important public holidays, is marked by a large military parade on Red Square and a moment of silence to honor the estimated 26.6 million Soviet lives lost during the war against Nazi Germany and its allies.
Some EU officials have argued that attending the celebrations in Moscow would be inappropriate given the ongoing conflict between Russia and Ukraine.
"Any participation in the May 9th parades - or celebrations - in Moscow will not [be] taken lightly on the European side, considering that Russia is waging a full-scale war in Europe," Kallas said following a meeting of EU foreign ministers in Luxembourg on Monday.
Asked whether the bloc is monitoring which countries plan to attend the event, Kallas responded that candidate nations should also refrain from taking part.
"We made it very clear that we do not want any candidate country to take part in the May 9 events in Moscow," she said. Kallas urged leaders of EU member states and officials to instead visit Kiev "as much as possible, to really show our solidarity and that we are with Ukraine."
Comment: Interesting that the EU does not want people to celebrate the victory over Nazism on the 9th of May in Moscow, but instead urges EU leaders and officials to go to Kiev, which has openly embraced nazi ideology.
According to Euractiv, Slovak Prime Minister Robert Fico is currently the only leader of an EU nation who has confirmed plans to attend the celebrations in Moscow. "It is natural that as Prime Minister of the Slovak Republic, I have a strong interest in participating in the official celebrations of the victory over fascism," he said last year.
The leaders of Serbia and Armenia, both EU candidate countries, have also indicated that they will attend. Russian President Vladimir Putin said earlier this month that Chinese President Xi Jinping will make a state visit to Moscow on May 9.
Earlier this month, German media reported that Berlin advised local institutions not to invite Russian or Belarusian officials to events commemorating World War II. Moscow responded by calling the move a "blatant insult" to the memory of the victims of the Nazis and fallen Soviet soldiers.
Comment: It follows recent ban by Germany of Russian participation in Victory day celebrations in Germany. See also: The Russian Foreign Ministry criticized Germany's ban on Russians' participation in Victory Day celebrations. It was after all, the Soviet Union which liberated the Auschwitz concentration camp.