Demonstrators attend a rally in support of Ukraine after Russian President Vladimir Putin authorized a military operation in eastern Ukraine, in Prague, Czech Republic, February 24, 2022. REUTERS/David W Cerny Thousands of Ukrainians fleeing war with Russia started arriving in neighboring central European countries on Thursday and the region braced for many more, setting up reception points and sending troops towards the borders to provide assistance. The countries on the European Union’s eastern flank were all once part of the Moscow-led Warsaw Pact and are now members of NATO. Among them, Poland, Hungary, Slovakia and Romania all share land borders...