If the West punishes Russia with sanctions and a trade war, that might be effective eventually, but it would also be cruel to the 140 million Russians who live under Mr. Putin's rule. And it would be unnecessary.
Instead, sanction the 140 oligarchs who would dump Mr. Putin in the trash tomorrow if he cannot protect their assets abroad. Target their visas, their mansions and IPOs in London, their yachts and Swiss bank accounts. Use banks, not tanks.
Thursday, the U.S. announced such sanctions, but they must be matched by the European Union to be truly effective. Otherwise, Wall Street's loss is London's gain, and Mr. Putin's divide-and-conquer tactics work again.