Belarus declared a national holiday on September 17, the same day Soviet Forces invaded Poland in World War II in 1939.
Poland has lashed out at Belarus after the country established a ‘Day of People’s Unity’ holiday on 17 September - the day that the Soviet Union invaded Poland and Ukraine during WW2.
Nazi Germany and the Soviet Union had signed the Nazi-Soviet Pact on 23 August 1939, under which they agreed to carve up Poland between themselves. Hitler's armies invaded Poland on September 1, while the USSR invaded on 17 September.
Belarus' decision comes amid heightened tensions with its neighbours and with the European Union after the regime of Alexander Lukashenko launched a brutal crackdown on pro-democracy protests.
In a statement, Poland's Ministry of Foreign Affairs said: “Founding Belarusian political history on the legacy of the Hitler–Stalin pact is utterly incomprehensible.
"This gesture, in line with Russia’s efforts to reinterpret very difficult history of our region, will seriously hinder Belarusian dialogue and understanding with neighbouring countries as well as all other European countries.”
"This date symbolizes restoration of historical justice"
Belarus was established as a modern European nation in 1991. It was previously part of the Soviet Union and partly controlled by Poland in the early 20th Century. For the millennium before that, it was in the so-called Polish-Lithuania Commonwealth and medieval Grand Duchy of Lithuania.
The Belarusian government press services says about the new holiday, “this date symbolizes restoration of historical justice and reunification of the Belarusian nation that was forcibly divided in 1921 in line with the Treaty of Riga. It is a special date in the history of the Belarusian nation.”
At the end of May this year, EU leaders initiated sanctions on Belarusian officials and banned Belarusian airlines from its airspace and airports. That's after a RyanAir flight carrying Belarusian journalist Raman Pratasevich was forced to reroute from Lithuania to Belarus, where he was arrested.
Russia has since denied a number of European flights access to its own air space, while trying to avoid Belarus.
Opposition leaders are calling for an international probe into Lukashenko, who remains in power despite widespread protests against his reelection last year.
Poland supports push for democracy in Belarus
Poland funds Belsat, a Warsaw-based TV station that broadcasts independent news into Belarus. Both Poland and Lithuania have welcomed Belarusian activists and students who live in exile.
“The establishment of a Day of People’s Unity to mark Belarus’s inclusion in the Union of Soviet Socialist Republics is the glorification of Soviet heritage and an attempt to cut Belarus off from its true roots. It is an act which undermines the independence and sovereignty of Belarus," Poland said.