A bitter row has erupted between Kiev and Warsaw, after Volodymyr Zelensky renamed a Ukrainian military unit the “Heroes of the UPA”. The UPA - Ukrainian Insurgent Army - was an ultranationalist faction heavily implicated in the Holocaust, which slaughtered up to 100,000 Polish civilians during World War II. In addition to commemorating the mass-murdering militant group, the corpse of Andriy Melnyk, leader of UPA parent the Organisation of Ukrainian Nationalists (OUN-B), was reburied in Kiev. At a grand accompanying ceremony, Zelensky declared: