Days after a top NATO commander warned of Russia’s military buildup on Ukraine’s eastern border, Russian troops staged military exercises in Moldova’s breakaway region of Transnistria, which borders Ukraine on the southwest, the Russian news agency Interfax reported Wednesday. "There is absolutely sufficient [Russian] force postured on the eastern border of Ukraine to run to Transnistria if the decision was made to do that, and that is very worrisome," U.S. Air Force Gen. Philip Breedlove, NATO's supreme allied commander in Europe, said Sunday at the Brussels offices of the German Marshall Fund of the United States, a Washington, D.C.-based...