“Today, we remember,” Mateusz Morawiecki, the Polish prime minister, wrote on the European Day of Remembrance for Victims of All Totalitarian and Authoritarian Regimes on Wednesday.

“Why August 23?” Morawiecki asked on social media.

“Because on that day, Germans and Russians signed the Molotov-Ribbentrop Pact, with a secret protocol, that divided Europe into spheres of interest, and which resulted in huge suffering and losses not only in Poland but also on the entire continent,” the prime minister wrote.

“Today, we remember. We are fighting for peace. We are strengthening the army. We are defending Poland,” Morawiecki said, noting that all this was necessary so that Polish children would never have to experience such tragic events.

The European Parliament decided in 2009 that each year, August 23 should mark the European Day of Remembrance for Victims of All Totalitarian and Authoritarian Regimes.

“With the Molotov-Ribbentrop Pact of August 23, 1939, Nazi Germany and the Soviet Union had divided Europe into spheres of interest. That agreement, with its secret protocols, preceded the German attack on Poland on September 1, 1939 and the Soviet occupation of eastern Poland, as well as the Soviet occupation and later annexation of the Baltic States, in June 1940,” the European Parliament wrote on its website.