One principle ought to be bred in the bone of any European after the carnage of the 20th century: that no act of state bears such ominous consequences as changing a border by force. Plenty of passionate voices said as much after Russian troops rolled into Georgia's breakaway province of South Ossetia on Aug. 8. On the night of Aug. 12, a day when Russian planes dropped cluster bombs on the town of Gori, the Presidents of Estonia, Latvia, Lithuania, Poland and Ukraine took the stage in front of the Georgian parliament building beside Georgian President Mikheil Saakashvili. "Everyone who believes...