And here we bump into the limits of central-bank sanctions as a financial weapon: A weapon that altogether crushes an adversary’s banking system may be just a little too powerful. The West wants to administer penalties that cause Russia to alter its aggressive behavior, not to crush the Russian economy. The central-bank weapon is so strong that it might indeed provoke Putin into fiercer aggression as a desperate last gamble. So the next question is: Is there any way to use the central-bank-sanctions weapon more incrementally?

Perhaps there is. Western banks do not need to freeze the Russian central bank’s accounts altogether. They could put the Russian central bank on an allowance, so many billions a month. That would keep Russia limping along, but under severe restraint—asphyxiation rather than sudden strangulation. The West could not prevent Putin from spending foreign currency on his war or favoring cronies in the distribution of foreign currency. But the restraint would rapidly make the terrible cost of Putin’s decisions much more rapidly visible to every power sector in Russian society. It’s not the full blow, but it might hurt enough—and of course, the full blow could be applied later.

The central-bank-sanctions tool will also deliver a humbling but indispensable lesson to Putin. Putin launched his war against Ukraine in part to assert Russia’s great-power status—a war to make Russia great again. Putin seemingly did not understand that violence is only one form of power, and not ultimately the most decisive.