Just when the crisis in Crimea appeared to be easing, it has suddenly grown more dangerous. In a decision that surprised even the peninsula’s pro-Russians, the local parliament has changed both the date and question for a referendum: On March 16, Crimea may vote to join Russia.

Any plebiscite held within 10 days of its announcement is by definition a joke, yet the implications here are serious: No major country has annexed territory since World War II. Unless it can be prevented, the damage will extend to everyone concerned. The move would, first of all, destabilize a fragile Ukraine, not least by encouraging pro-Russians in other regions to follow Crimea’s example. Civil war would become difficult to avoid.

Crimea would pay a special price. Despite the province’s history and its majority Russian population, most Crimeans have not favored secession from Ukraine to join Russia, opinion polls suggest. For such a choice to be widely accepted, a rigorously managed and monitored vote on self-determination would be essential, and that can’t be arranged in 10 days.

The shotgun marriage on offer is bitterly opposed by Crimea’s 12 percent ethnic Tartar minority, who were victims of genocidal policies directed from Moscow under Stalin in the late 1940s; their leader has already called on Tartars to boycott the vote.

Europe and the U.S. would suffer, too. Unable to accept Russia’s annexation of territory, they would be forced to enact punitive economic sanctions that would lead to a new kind of Cold War. Differences among Russia’s major trading partners ― Germany, for one ― and countries that have historic ties to Ukraine or fear Russian expansionism ― Poland and the Baltic states ― would strain the alliance.

And Russia would pay its own heavy price for President Vladimir Putin’s claiming legal title to beachfront property and a naval dockyard in Crimea. Already, the central bank in Moscow has spent more than $11 billion to steady the ruble. With its much smaller economy, Russia would not be able to compete with Western sanctions.

Most of all, a decision to gamble with international isolation would make it all but impossible for Russia to build an open-market economy that is capable of producing wealth beyond the corrupting riches of oil and gas.

One way to create the space for a solution is for both Europe and Russia to agree that Ukraine will not join any economic union for now. (A dispute over whether Ukraine would become part of either a Russian or a European coalition is one of the causes of the current crisis.) As part of such a deal, all discussion of Western sanctions against Russia would need to end.

The decisive next move will be Putin’s: Crimea’s government can engineer a vote for unification with Russia, but he is not obliged to accept it. Putin himself once said that “whoever does not miss the Soviet Union has no heart, whoever wants it back has no brain.” In annexing Crimea, he would be ignoring his own good advice.

He can instead uphold the principles of sovereignty he professes to believe in, and he should be offered a path to do so.

(Bloomberg)