(Corrects paragraph 14 to reflect sanctions on elites will begin on Tuesday, not Wednesday, after White House issued corrected transcript) By Tom Balmforth, Polina Nikolskaya and Steve Holland MOSCOW/DONETSK/WASHINGTON (Reuters) – Western nations on Tuesday punished Russia with new sanctions for ordering troops into separatist regions of eastern Ukraine and threatened to go further if Moscow launched an all-out invasion of its neighbour. The United States, the European Union and Britain announced plans to target banks and elites while Germany halted a major gas pipeline project from Russia, wh…