BRUSSELS, June 9 -- Ursula von der Leyen had a number in mind when she stepped up to address reporters at the European Commission on Monday: twenty-one. Not a milestone she treated as symbolic. A data point she treated as evidence.

"Our sanctions are working," the Commission president said, announcing the 21st package of EU restrictive measures against Russia. "They are weakening the economic foundations of Russia's war effort." The constancy of that effort, she argued, is precisely what is paying off - a framing that speaks less to the specifics of this particular package than to the political question Brussels has been quietly arguing over for two years: whether incremental pressure still adds up to anything.

The answer the Commission...