Immediately after the Turkish president, Recep Tayyip Erdoğan, quelled a military coup attempt in 2016, he detained 77,000 people, including 10,000 soldiers.

When President Putin faced a similar military mutiny last month, he went on national television and called the mutineers “traitors.” Yet five days later, he held a secret, three-hour meeting to allow coup leader Yevgeny Prigozhin and 35 commanders to air their grievances. 

Later, Mr. Prigozhin’s men reportedly drove around St. Petersburg, picking up their guns, gold, and dollars that had been confiscated by police.

“Erdoğan’s reaction to the failed 2016 coup in Turkey showed no such mixed messages,” a former American assistant secretary of state for Europe, Daniel Fried, writes for the Atlantic Council. “Erdoğan might have concluded that betting on Putin after the mutiny seemed less wise.”

This sharp contrast may explain why Turkey tilted sharply last week — away from Russia and toward Ukraine. Bearing a gift to today’s NATO summit at Vilnius, Mr. Erdoğan reversed course and endorsed Sweden’s entry into NATO. 

Coming after Finland joined NATO in April, the addition of Sweden will turn the Baltic into a NATO sea. Within hours of the announcement, the White House said it would sell $20 billion worth of F-16 fighter jets to Turkey.

Over the weekend, Mr. Erdoğan hosted President Zelensky at Istanbul. In a series of surprise moves, the Turkish leader said that NATO should admit Ukraine as a member, vowed that Turkey would expand sales of Bayraktar military drones to Ukraine’s Army, and aired the possibility of Turkish naval vessels escorting Ukrainian grain shipments through Russia’s Black Sea blockade. 

Mr. Zelensky flew home from his two-day visit with concrete trophies: five Ukrainian military commanders who had been freed by Russia on the condition that they not return to Ukraine until the war is over.

Russia immediately accused Turkey of breaking its part of a prisoner swap deal. To mollify Moscow, Mr. Erdoğan said he would host Mr. Putin in Turkey next month. Highlighting Russia’s growing isolation, Moscow ordered the closing of Finland’s consulate at St. Petersburg. 

In quieter days — a decade ago — the consulate claimed to be the busiest diplomatic office in Europe, handing out a million visas a year to Russians going to Finland for  shopping.

Despite Kremlin attempts at damage control, Mr. Putin’s image — at home and abroad — has been damaged by his Prigozhin flip-flop.

“After the Prigozhin mutiny, Erdogan sees Putin’s weakness,” London-based financial analyst Timothy Ash wrote Monday to his clients. “Turkey thinks, post the Prigozhin mutiny, that Ukraine will win, and Putin is damaged goods and likely on his way out.”

The mutineers may have been more dangerous than originally believed. On Monday, Reuters reported that Mr. Prigozhin’s soldiers sought to increase their bargaining power by trying to get suitcase nuclear bombs. 

Based on interviews and videos, Reuters established that one dozen armored vehicles peeled off from the main convoy of mutineers and traveled east, aiming for Voronezh-45, a Russian nuclear storage base. 

Ukraine’s head of military intelligence, Kyrylo Budanov, told Reuters that the mutineers reached the base perimeter and their intention was to acquire small Soviet-era nuclear devices in order to “raise the stakes” in their mutiny.

 At home yesterday, nationalist Igor Girkin asked on Telegram why Mr. Putin met with Mr. Prigozhin and the 35 leaders of his Wagner mercenary group. “Will there be a photo of 35 ‘musicians’ swindling and making a fool out of the president too?” Mr. Gherkin asked.

Referring to the 20 or so airmen killed by the mutineers, Mr. Girkin added: “And will Putin receive the parents and widows of the killed pilots, or ‘that’s a different story?’”

On Sunday, police raided the St. Petersburg office of Listva, a right-wing nationalist center where Mr. Girkin was scheduled to speak. Mr. Girkin gave the speech at another location.

Behind the Kremlin’s cautious moves, Mr. Prigozhin has a popular following. After a series of blunt attacks in Russia’s high military command, his approval rating with the Levada polling group hit 58 percent in early June. 

After leading his June 24 “March on Moscow,” Mr. Prigozhin saw his Levada approval rating drop in half to 29 percent.

Part of Mr. Prigozhin’s popularity may stem from his fleeting fame as a man who speaks truth to power. Despite strict wartime censorship, Russians seem to realize that the war is not going well for Russia.

On Monday, two Russian exile publications, Mediazona and Meduza, posted the results of their detailed study of the costs of the war during the first 15 months: 45,000 Russian soldiers dead and 125,000 soldiers wounded seriously enough to win a discharge. 

By contrast, during the decade-long Soviet occupation of Afghanistan, the Soviet Union lost 14,453 soldiers dead and 53,573 wounded. In the 1980s, the Soviet Union had a population of 288 million — twice as large as Russia’s today.