Zelenskyy honors victims of World War II massacres of tens of thousands of Poles carried out by Ukrainian nationalists

• Volodymyr Zelenskyy attended a memorial service with the Polish President on Sunday.
• They honored the Polish victims of World War II massacres carried out by Ukrainian nationalists.

Ukrainian President Volodymyr Zelenskyy attended a memorial service on Sunday which honored the Polish victims of massacres carried out by Ukrainian extremists.

Images shared by Zelenskyy's Twitter account showed him and Polish President Andrzej Duda in a church in Lutsk, a city in western Ukraine.

"Together, we honor all the innocent victims of Volyn," Zelenskyy said on Telegram. "Memory unites us! Together we are stronger!"

Tens of thousands of Poles in Volhynia — a historic eastern European region that is primarily in Ukraine's Volyn Oblast but includes parts of Poland — were killed by extreme Ukrainian nationalists between 1943 and 1945.

The Ukrainian Insurgent Army was a nationalist paramilitary and partisan formation founded by the Organization of Ukrainian Nationalists. At times, it fought alongside Hitler's Nazis and provided the Third Reich with auxiliaries who committed the mass murder of Jews in the Holocaust.

Estimates for the death toll during the World War II ant-Polish massacres range from 20,000 to 100,000, The New York Times previously reported. Polish historians also say up to 12,000 Ukrainians were killed in retaliation, per Reuters.

In 2016, Poland's parliament officially declared the massacres genocide, provoking tensions with Ukraine. But since Russia invaded its neighbor, Poland has become one of Ukraine's staunchest supporters, donating 330 tanks.

Several days of observances honoring the victims began on Friday when Polish Prime Minister Mateusz Morawiecki traveled to Ukraine to visit massacre sites, the Associated Press reported.

Zelenskyy's recognition of those atrocities does not go as far as joining Poland in calling it a genocide, but it is still symbolically important.

Even as Vladimir Putin uses "denazification" to justify the ongoing conflict, the Ukrainian president is confronting Ukraine's dark history during World War II.

"Without the full clarification and full record of the Volhynia crimes, Russia will always be using this card to drive a wedge between Poles and Ukrainians," Morawiecki said, per the AP.