For centuries, the diverse peoples of the crowded area known as the Balkans have exploded regularly in unspeakably cruel wars, many of which spilled over into areas far beyond their borders. In the process, the Balkans —Yugoslavia, Rumania, Bulgaria, Albania, Greece and the European part of Turkey—became famous as a scene of intrigue and espionage. Mystery writers from Agatha Christie to Eric Ambler drew on the area for some of their best plots.
Now the Balkan countries are making an attempt to change the old script. Last week, in an act that in effect ended a 31-year undeclared state...