But real trouble can flow even from a farce. Thinkers for whom Russia was just one problem in a world full of problems, who previously did not identify Moscow as the No. 1 enemy, now do so, vociferously, for fear of being lumped in with Mr. Trump as a traitor to America or some such.

A mob is a machine for mass-producing cowards and bullies. That’s where we are now. Just turn on cable TV.

Even the estimable Anne Applebaum, author of a book on the Soviet gulag, fulminates in the Washington Post against every recent president for failing to heed Russia’s “peculiar dangers.” With all due respect, U.S. presidents are better informed than anybody about the nature of the Russian regime. They read the intelligence. George W. Bush looked in Mr. Putin’s eyes and didn’t see his soul. He saw a potential nightmare that would have to be managed somehow. Ditto President Obama.

But neither are U.S. presidents equipped with magical powers to make such facts go away.