(Reuters) - The United States and Europe exchanged angry words with Russia on Saturday in a tug-of-war over Ukraine, with U.S., EU and NATO leaders saying Moscow must not strong-arm Kiev into an unpopular alliance. At conference in Munich where Western diplomats met leaders of the Ukrainian opposition, United States Secreatary of State John Kerry said the protesters believe "their futures do not have to lie with one country alone, and certainly not coerced". "Nowhere is the fight for a democratic, European future more important today than in Ukraine," he said. "The United States and EU stand with the people...