The “next Crimea,” Berman suggests, is more likely to be the northeast of Estonia. The city of Narva there, the Baltic state’s third largest, has an 82 percent ethnic Russian population. 94 percent of the city’s residents speaks Russian. Like the Crimea’s Sevastopol, which headquarters Russia’s Black Sea Fleet, Narva was a Russian port city and the site of major battles — against the Swedes, in the early eighteenth century, and the Germans, during World War II.

Russia justified its intervention in Ukraine by claiming a right to protect Russian speakers and “compatriots” in the former Soviet republic. Last week, a Russian diplomat raised concerns over the treatment of Russian speakers in Estonia, saying, “Language should not be used to segregate and isolate groups,” and expressing alarm “by steps taken in this regard in Estonia as well as in Ukraine.”

Russian worries are not without merit. As Berman writes, “Narva is a major symbol of what is one of Estonia’s largest domestic problems, its effort to reduce the size of its Russian minority population through the mechanism of denying a substantial percentage of its residents citizenship.”

Less than half of Narva’s residents have Estonian citizenship while some 36 percent are Russian citizens. Another 16 percent holds no citizenship at all.

Social problems disproportionately affect Estonia’s Russian speakers, from unemployment to crime to drug and alcohol abuse. 40 percent of Narva’s residents is jobless and the city has one of the highest HIV rates in Europe.