BELGRADE, Serbia — Serbia’s strongman leader, Aleksandar Vucic, is fed up with being reviled as a “little Putin” intent on aggression against his country’s fragile neighbors in the Balkans.

For starters, Mr. Vucic noted wryly in an interview in the library of the presidential palace this month, “I am almost two meters tall.” That makes him about 6-foot-5. (Vladimir V. Putin is an estimated 5-foot-7 at most, though the Russian president’s exact height, a sensitive topic for the Kremlin, is a secret.)

Behind Mr. Vucic’s levity over physical stature, however, lurks a serious question that torments the Balkans and preoccupies Western diplomats.

Is Russia, mired in a brutal war in Ukraine, using Serbia to stir division in Europe and provoke renewed conflict in the former Yugoslavia to distract NATO from the battle raging to the east?

Those fears flared last week when an esoteric dispute over license plates between Serbia, which is bound to Russia by history, religion and deep hostility toward NATO, and the formerly Serbian province of Kosovo led to unruly protests, roadblocks and gunfire — setting off alarm bells in the Atlantic alliance.

The unrest in Kosovo, and strains in nearby Bosnia and Herzegovina caused by Milorad Dodik, the belligerent, Moscow-backed leader of the ethnic Serb enclave there, and by hard-line Croat nationalists have led to warnings that Russia is trying to stoke tensions, stilled but never really resolved, from the Balkan wars of the 1990s.

“Russia calculates that the more time the West spends sweating in the Balkans, the less time it will spend sweating in Russia’s backyard,” said Vuk Vuksanovic, a researcher at the Belgrade Center for Security Policy.

“But there are limits on what Russia can do,” Mr. Vuksanovic added. “It needs local elites and these don’t want to be sacrificed for Russian interests.”

America’s ambassador to Serbia, Christopher R. Hill, a veteran diplomatic troubleshooter whose recent appointment signaled Washington’s heightened anxiety over the Balkans, said that Russia, offering only “economic blackmail” and “chaos throughout the region,” had found few takers.

“Despite Russia’s influence on Serbia’s energy sector and despite its pervasive disinformation efforts here, Serbs have decided that their future is with Europe and the West,” Mr. Hill said.

Russian news outlets and social media accounts have for months pumped out incendiary reports of ethnic Serbs in Kosovo and Bosnia suffering intolerable oppression. The reports, which largely reprise Russian propaganda about the suffering of ethnic Russians living in Ukraine, have emboldened hard-line, pro-Moscow Serb nationalists.

Anger among the around 65,000 ethnic Serbs who still live in Kosovo, inhabited mostly by ethnic Albanians and wrenched from Serbian control by a NATO bombing campaign in 1999, has simmered for years. But tensions spiked dangerously on July 31 in response to a plan, later postponed, by the Kosovan authorities to ban Serbian license plates and identity documents starting Aug. 1.

Slavisa Ristic, former mayor of Zubin Potok, a town in northern Kosovo inhabited almost entirely by ethnic Serbs, said that he would never voluntarily put Kosovan plates on his car because that would mean recognizing Kosovo’s independence, something that nearly all Serbs, including President Vucic, say is out of the question.

Borko Stefanovic, an opponent of Mr. Vucic who chairs the Serbian Parliament’s foreign affairs committee, said that the car plates issue was “so minuscule it is absolutely ridiculous.”

“But,” he added, “here in the Balkans, such symbolic things are of huge importance.”

Last week, Jens Stoltenberg, NATO’s secretary general, tweeted that he had spoken with Mr. Vucic about the flare-up in Kosovo, declaring that the alliance, which leads a peacekeeping mission in the former Serbian territory, “stands ready to intervene if stability is jeopardized.”

Also calling for calm has been Mr. Hill, the U.S. ambassador. In an interview in Belgrade, the Serbian capital, Mr. Hill said that while he considered armed conflict unlikely he had told Mr. Vucic: “Wars have started over land, money, even a beautiful woman. But this would be the first war I’ve ever heard of that was started over a license plate.”

Rife with potential flashpoints, both symbolic and of substance, the lands of the former Yugoslavia replicate on a smaller scale the forces at play in Ukraine: a regional hegemon, in this case Serbia, seething over lost territory and scattered ethnic kin; and a geopolitical tug of war between Russia and the West.

A senior legislator from Mr. Vucic’s party, Vladimir Djukanovic, has seized on the idea of Serbia as an avenger that “will be forced to begin the denazification of the Balkans,” an ominous echo of Russia’s stated goal in Ukraine and of Belgrade’s pursuit of a “Greater Serbia” in the 1990s.

Mr. Vucic, who publicly denounced Mr. Djukanovic’s statement as “stupid” and “irresponsible,” said: “We have our country. We are not interested in expanding our borders and getting into any fights with our neighbors.”

The Russian Foreign Ministry added fuel to the Kosovo fire last week by accusing ethnic Albanian “radicals” of trying to eject ethnic Serbs from the territory and of provoking unrest “to launch a violent scenario.”

Mr. Putin has repeatedly cited NATO’s military intervention in support of Kosovo’s separation from Serbia in 1999 as a justification for Russia’s aggression against Ukraine, which he claims is to protect ethnic Russians in Donetsk and Luhansk.

“Putin is using and smartly learning from your mistakes, which you are never going to admit,” Mr. Vucic said, referring to the West.

Most Western countries recognize Kosovo as an independent state, but other nations, including Serbia, Russia, China and five European states do not.

“Kosovo for Russia is the perfect low-cost investment that just keeps on giving,” said Mr. Vuksanovic, the Belgrade-based researcher. Nonetheless, he added, Russia’s capacity for mischief-making in the Balkans has been severely constrained by the war in Ukraine.

“There is less now that Russia can actually do. Its abilities are more limited and it is more isolated. Its resources are focused on Ukraine,” he said.

Take, for example, Mr. Dodik. Boasting of strong support from Russia, the Bosnian Serb leader provoked a potentially violent crisis late last year with a vow to set up his own ethnic Serb army and effectively secede from Bosnia-Herzegovina.

Yet in April, two months into the war in Ukraine, Mr. Dodik suddenly announced that he was postponing his secessionist plans. “He looked at Ukraine and saw how the West reacted to Russia. He realized that he had to tone things down,” Mr. Vuksanovic said.

While Russia has been widely accused of encouraging Mr. Dodik’s secessionist ambitions, Mr. Vucic is credited by diplomats in the region with helping rein them in.

Mr. Vucic said that he had spoken to Mr. Dodik about his secessionist project but declined to say what he had told him. “Serbia,” Mr. Vucic added, “has always supported the territorial integrity of Bosnia” as defined by the 1995 Dayton peace agreement.

Mr. Vucic said that he had nothing to do with the recent protests over the license plates in northern Kosovo, saying that ethnic Serbs there were “100 percent fed up,” particularly with the Kosovar government’s refusal to implement key parts of a 2013 agreement that promised them a measure of self-rule.

Beneath layers of intrigue and local political feuds, however, one thing seems clear: “We are caught in a proxy war like Ukraine, only on a much smaller scale,” said Mr. Stefanovic, the Serbian foreign affairs committee chairman.

That struggle, lamented Mr. Vucic, has put his country in a painful vise, squeezed between dependency on Russia for energy and diplomatic support over Kosovo, and demands from Western powers that it join efforts to punish Moscow for the Ukraine invasion.

“I get pressure from them every single day to impose sanctions on Russia,” Mr. Vucic said. That, he added, will not happen, at least not until Serbia’s stalled, 13-year-old application to join the European bloc picks up speed. (More than 80 percent of Serbs oppose sanctions on Russia, according to a recent opinion poll.)

To Moscow’s fury, Serbia in March backed a United Nations resolution demanding that Russia halt its invasion, a vote that led to an uproar from radical Serb nationalists, who denounced Mr. Vucic as a “traitor.”

But Serbia’s refusal to implement sanctions has provided ammunition to those who view Mr. Vucic as a Russian puppet.

Noting that Serbia “remains the only country in Europe that refuses to sanction Russia,” the prime minister of Kosovo, Albin Kurti, in April denounced Mr. Vucic as “Serbia’s little Putin.” “Peace and security in the Western Balkans have never been more threatened,” he said.

Mr. Vucic dismissed Mr. Kurti’s accusation.

“Kurti wants to be a ‘little Zelensky’ fighting ‘little Putin,’” Mr. Vucic said, referring to Ukraine’s president, Volodymyr Zelensky. “This is his narrative — that Vucic is a terrible nationalist who wants to fight against everybody.”

“It is not true at all,” he added.

But, with so much pressure bearing down on Serbia from all sides, Mr. Vucic conceded, “We are stuck, and we know this.”