The convoluted plot twists and bravura posturing might seem reminiscent of a comic opera. Certainly the so-called Dniester Republic (pop. 600,000) is among the miniest of ministates, proclaimed by ethnic Russians and Ukrainians seceding from a secession. Its citizens refused to stay in the new nation of Moldova (pop. 4.4 million), a former Soviet republic that broke away from Moscow last August, because the majority ethnic Romanians were making noises about uniting with their brethren across the border.
But in little more than a week the story has turned into a blood-soaked tragedy with ominous international implications. As many as 500...