Russian President Vladimir Putin seems confident that he has again outflanked the decadent democracies of the West. He is satisfied that he has convinced important segments of world public opinion that Russia’s invasion of Ukraine was a justified response to Western threats to Russian security—and not, as it was, punishment for Ukraine’s embrace of Europe.

While we in the West debate the point, Mr. Putin is busy creating new realities on the ground. He is immensely aided in this effort by a Russian propaganda machine that buoys his popularity at home and disseminates his cracked version of history through digital networks around the world. Mr. Putin is succeeding militarily—and winning the war of words.

Unless the U.S. and its allies wrest the rhetorical high ground from Russia, Mr. Putin will retain the initiative and a military confrontation may become inevitable. As he avidly rewrites history, he may also be able to weaken the democratic narrative as the defining principle of post-Cold War Europe. The negative effects of such a development would stretch far beyond Ukraine and Europe.

Current measures ostensibly meant to address Moscow’s concerns—as with an experts’ group on European security structures convened by the Organization for Security and Cooperation in Europe, whose members include much of Europe, the U.S. and Russia—make things worse by offering prolonged discussions while the Kremlin pursues its real goals. Ukraine is well on its way to becoming another one of the “frozen” conflicts in former Soviet republics that are Mr. Putin’s special method of keeping his “near abroad” under control.