In WWII Ukranian nationalists collaborated with the Nazis. There was also a lot of anti-semitism. Ukranian Jews were the first to be wholesale slaughtered I think. The death camps didn't exist yet when the Germans took and occupied Ukraine, in fact it was the mass killings in Ukraine and the psychological effect it had on the Nazis assigned to kill Jews that led them to come up with the idea of mobile gas vans and then gas chambers so massive numbers of Jews could be killed without worrying the consciences of the poor sensitive Nazis. Gutless psychopaths then built the gas chambers and forced the Jews to do most of the dirty work killing their fellow Jews.
There were heroes among the Ukranians who risked their lives to save Jews. This Catholic priest saved hundreds and lost his life for doing so.
"During his visit to Ukraine, Pope John Paul II beatified one of the righteous - Father Omelyan Kovch who sacrificed his life while saving several hundred of Jews. In 1942, father Kovch issued Jews large numbers of baptism certificates in attempt to save their lives. In doing so, he broke the Nazi prohibitions and so he was arrested in December 1942 and deported to the Majdanek concentration camp where he was gassed and burned on March 26, 1943."
And people still believe God exists, what a life ol' Yaweh has, gets credit for everything wonderful in the world but when the most terrible shit happens, he's never to blame, don't even think about asking him why, he won't take your call.