PRAGUE (Reuters) -The European Union is preparing for “millions” more refugees fleeing Russia’s invasion of Ukraine, EU Home Affairs Commissioner Ylva Johansson said on Tuesday. Johansson said it was difficult to estimate precisely how many refugees could stream through EU borders after Russia invaded Ukraine last week, after more than 400,000 had come through so far. Many of those fleeing have met long waits at crossings into Poland, Hungary, Slovakia and Romania, the EU states bordering Ukraine. “Unfortunately, we have to prepare for millions of people to come,” Johansson told a news confere…