Mr. Putin has moved to fill the void left by American inaction; he is attempting to displace the U.S. as the region’s dominant outside power. The Russians say they are bombing ISIS, but there is little evidence of that. By all accounts they are bombing U.S.-backed rebels. Mr. Putin is attempting to prop up his client Bashar Assad, and sending a message to radicals and extremists who may one day move on Russia. An imposed Syrian stability is in Moscow’s interest: He’ll show the destabilizers who’s boss. He is—once again!—asserting Russia’s place as a force in the world. He is trying to demonstrate to America’s allies that Russia is a better bet, either as a reliable friend or a dangerous foe.

Mr. Putin’s move is worse than a snub to President Obama. It’s an insult, a cuffing.

It is generally assumed Mr. Putin moves in other nations to whip up nationalist fervor and bolster his position at home. That would likely be a side benefit to this venture, not a motive. Is he moving to humiliate Mr. Obama? That would be a side benefit, too. He means to emerge as top dog. Old Putin cliché: He’s a whacked-out would-be czar riding shirtless on a horse. Emerging Putin cliché: “This guy means business.” He’s a deadlier and more acute strategic thinker than has been appreciated. He’s one cool customer.

Part of what has happened is due to the president’s habitual cloud-talking. In cloud-talking you say words into the air and then ask: “Isn’t that a pretty cloud?” Since 2011 the president has been saying, “For the sake of the Syrian people, the time has come for President Assad to step aside.” Now he uses the word transition—Syria must “transition” away from Assad. Stepping down, red lines, transitions—the cloud-talk enters the air, has no force, and disappears. The world is impressed by actions.