Poland’s prime minister Donald Tusk called for solidarity and talks between Warsaw and Kyiv on Monday after diplomatic relations deteriorated over the naming of a ?Ukrainian army unit for nationalist insurgents who massacred Poles in the second World War.Ukrainian president Volodymyr Zelenskiy caused outrage in Poland last month by renaming an army unit after the Ukrainian Insurgent Army (UPA) that fought in the 1939-45 war. The dispute has dragged Ukraine’s relations with one of Kyiv’s staunchest supporters since ?Russia’s 2022 invasion to a new low as Kyiv seeks to bolster support for its efforts to join the European Union. A...