STAVROPOL, Russia — Outside Stavropol’s police headquarters recently, a priest in a purple velvet hat and gold stole moved from one man to the next, offering a cross to be kissed and drenching their faces with holy water from a long brush.

And so began another night of law enforcement as Cossacks, the fierce horsemen who once secured the frontier for the Russian empire, marched out to join the police patrolling the city.

In his third term, President Vladimir Putin has offered one clear new direction for the country: the development of a conservative, nationalist ideology. Cossacks have emerged as a kind of mascot, with growing financial and political support.

The Kremlin is dipping into history: Cossacks are revered in Russia for their bravery and code of honor, like cowboys in the United States or samurai in Japan. But their legacy is bound up with battle and vigilante-style violence, including campaigns against Turks, Jews and Muslim highlanders.

These days men in Cossack uniforms are making appearances all over Russia, carrying out raids of art exhibits, museums and theaters as standard-bearers for a resurgent church.

But in Stavropol on Russia’s southern flank, the Cossack revival is more than an idea. Regional leaders are granting them an increasing role in law enforcement, in some cases asking them to stem an influx of ethnic minorities, mainly Muslims from the Caucasus, into territory long dominated by Orthodox Slavs.

“We’ve lived cheek to cheek with them, and sometimes we fought with them, and we probably understand them better than a Russian from Moscow,” said Staff Capt. Vadim Stadnikov, head of security for the Terek Cossack Army, whose office displays a portrait of Czar Nicholas II. “They respect strength here.”

“With police it is a short conversation; you committed a crime, here’s the punishment,” he said. With Cossacks involved, he added: “There is a prophylactic effect, a kind of education. They come here. Take this group of young people. Explain to them the traditions of the Orthodox, Slavic, Cossack people of the city of Stavropol. What our rules are. How we live here.”

Potential for trouble

A series of violent episodes has underlined the potential for trouble. This month, a Cossack chieftain was fatally shot trying to arrest a drunken man who had taken hostages in the neighboring region of Krasnodar. At the chieftain’s funeral, Cossacks in crimson coats, carrying leather whips and sabers, streamed after a riderless horse, a sight that could have dated from the 16th century.

Afterward, a top official said the time had come for the state to allow Cossack patrolmen to carry traumatic guns, nonlethal weapons that can inflict severe injuries at close range — a proposal that has been endorsed by the governors of Krasnodar and Stavropol.

“Some human-rights activists, some ill-wishers, talk a lot about whether it’s necessary or not necessary,” Nikolai Doluda, chieftain of the Kuban Cossack Army and a deputy to the governor, told Russian television. “This terrible, frightening event underlines the fact that it is necessary.”

Historians still argue about who the Cossacks were: descendants of escaped serfs or Tatar warriors, an ethnic group in their own right or a caste of horsemen. They played a crucial role in colonizing the south for the Russian empire and later turned on peasant and worker uprisings, defending the czar.

The Bolsheviks nearly obliterated them, deporting tens of thousands in a process they called “de-Cossackization,” but the image of the Cossack, wild and free, was a permanent part of the Russian imagination.

When Leo Tolstoy sat down to write “The Cossacks,” he set it near present-day Stavropol, where the Terek River divided the Muslim-populated mountains from the steppes, which were Cossack country. In a scene taught to generations of schoolchildren, a young Cossack spots a Chechen swimming across the Terek disguised as a log and shoots him.

The notion of an ethnic dividing line is widely accepted to this day, but it is running up against demography. Muslim ethnic groups in the Caucasus have a high birthrate, and Russians are abandoning the steppe. About 81 percent of Stavropol’s population is ethnic Russian, but that share has been shrinking, the International Crisis Group has reported.

This rapid change is unsettling to ethnic Russians in Stavropol. Gennady Ganopenko, 42, said he grew up in a city so homogeneous that “the sound of a non-Russian language was grounds for a brawl.”

“Earlier, this was the gate to the Caucasus,” he said. “We opened the gate, and then the gate came off the hinges.”

“A Cossack can”

The Cossack revival seeks to slow this trend. Last summer, Aleksandr Tkachev, the governor of the Krasnodar region, to the west, took aim at his neighbors in the Stavropol region, saying so many Muslims had resettled there that Russians no longer felt at home. The region, he said, no longer served its traditional function as an ethnic “filter.”

To crack down on illegal migration, he announced creation of a salaried force of 1,000 Cossack patrolmen, which — he said in a speech to law-enforcement officers — would not be restrained by the law as the police are. He put it this way: “What you cannot do, a Cossack can.”

The Cossacks who set out to patrol Stavropol on a recent night believed they were part of a rising tide. Andrei Kovtun, 29, recalled the ribbing he got from his former colleagues in law enforcement when he first patrolled with the Cossacks, who do not have the right to demand documents, carry weapons or detain people.

Still, on one of his early calls — separating two groups of brawling men — he understood that a Cossack’s presence had a psychological effect. “Are you a cop?” someone asked him, and when he answered no, the room went quiet. Kovtun understood why: Policemen are bound by the law.

“A complaint cannot be made against a Cossack, and a Cossack cannot be fired,” he said. “They know Cossacks are free and will not think too much about how to take a violator to a police station, but will simply give him a whipping. This is what people are afraid of — that a Cossack will punish the culprit in the old, traditional but fair fashion.”

“However,” he added, hastily, “first we should always stop it by force of persuasion.”