In late September, Serbia deployed advanced weapons to its border with Kosovo, in what amounted to one of the largest Serbian military buildups since the end of the Kosovo war nearly a quarter century ago. In the United States, a spokesman for the National Security Council called it “an unprecedented staging of advanced Serbian artillery, tanks, and mechanized infantry units.” U.S. Secretary of State Antony Blinken called Serbian President Aleksandar Vucic to demand an “immediate de-escalation.”
Although the buildup was largely overlooked by Western media at the time—and has since been forgotten amid the outbreak of war between Israel and Hamas—it is part of an alarming development in the Balkans. The immediate pretext for the Serbian mobilization was months of unrest between Kosovo and Serbia, which have maintained a fragile peace ever since a NATO bombing campaign helped Kosovo win de facto independence from Belgrade in the 1998–99 war. In May, Serbia placed its troops on combat alert after ethnic Serbs living in Kosovo clashed with Kosovo police. And then in September, just before the recent mobilization at the border, 30 heavily armed ethnic Serbs attacked a police patrol in Kosovo, leaving four people dead.
But there are many indications that these incidents go beyond the familiar tensions that persisted in past years. These incidents also show the growing threat that Russia, Serbia’s partner, is posing to the region. In 2022, for example, Serbian Prime Minister Ana Brnabic said that Kosovo and Serbia were “on the brink of armed conflict.” And Moscow—which does not recognize Kosovo’s independence—fanned the flames, using information operations to fuel Kosovar-Serbian distrust and to spread hawkish messages that polarize the region along ethnic and religious lines. Russia has also armed Serbia while increasing Serbia’s energy dependence on its companies by providing gas and oil at a sharp discount. Moscow has promised Belgrade that it will block Kosovo from becoming a UN member state. “A big explosion is brewing in the center of Europe,” Russian Foreign Minister Sergei Lavrov said in May. It might have been a boast.
Part of why Russia is happy to stoke the historical conflict between Kosovo and Serbia is because doing so stresses NATO resources and undermines U.S. power in Europe. NATO forced Serbia to pull out of Kosovo in 1999, and the alliance has maintained a small peacekeeping force of NATO troops in the latter country ever since. As a result, rising tensions between Kosovo and Serbia test NATO’s staying power in the region. Backing Serbia also gives Russia a foothold in the Balkans. Serbian officials have thanked Russia for its “support for Serbia’s territorial integrity and sovereignty” and have stressed that Moscow’s support is the reason Serbia refuses to impose sanctions on Russia.
By putting pressure on Belgrade, the United States was able to calm the most recent bout of unrest, with Vucic declaring a few days later that he would draw down forces on the border and that Serbia had no intention of invading Kosovo. But tensions remain high. Kosovo has labeled the September attacks terrorism, while Vucic has charged Kosovo with perpetrating a “brutal ethnic cleansing” against ethnic Serbs in Kosovo with the help of “the international community.” And Vucic does not need to pursue a full-blown military campaign in Kosovo to further his project of destabilizing the country and humiliating NATO. Like Russian President Vladimir Putin, Vucic uses paramilitary groups to advance his aims. According to Kosovo’s government, Belgrade helped orchestrate the September attack. Vucic could use “little green men” to seize control of northern Kosovo while maintaining plausible deniability, just as Putin did in Crimea.
It is time, then, for NATO to decisively put an end to Vucic’s Kremlin-enabled sideshow. The United States and Europe must make it clear to Belgrade and Moscow that they will react strongly, and harshly, to future Balkan provocations. They must strengthen NATO’s presence in the region and establish credible redlines that Serbia cannot cross without provoking a military confrontation with NATO forces. And they must sanction Belgrade if Serbia’s leaders do not move away from Moscow and de-escalate tensions.
AXIS OF CONVENIENCE
Vucic’s emergence as a key instigator of tensions with Kosovo should not come as a surprise. As a young politician, Vucic was a hardcore Serbian nationalist. During the Balkan wars that followed the collapse of Yugoslavia—in which Albanians, Bosnian Muslims, Croatians, and Serbs killed each other as they tried to control the region—Vucic encouraged the new Serbian state to crush its ethnic opponents. He felt particular vitriol for Kosovar Albanians, who are mostly Muslims and make up more than 90 percent of Kosovo’s population. “For every Serb killed, we will kill 100 Muslims,” Vucic declared in a 1995 address. In 1998, he became Serbian President Slobodan Milosevic’s minister of information. Milosevic’s regime, infamous for its particularly brutal killing of Albanians, fell apart after NATO’s intervention. Milosevic was arrested for war crimes by the International Criminal Tribunal for the Former Yugoslavia. He died in prison before he could be convicted.
Today, Vucic is more of an opportunist than a nationalist, driven largely by his desire to remain in office and expand his power. But this new motivation has not made Serbia’s president particularly benevolent. Vucic benefits politically from chaos in the Balkans, which helps him justify his political relevance and maintain control. A crisis in Kosovo, for example, helps Vucic divert attention from his own domestic political issues and tamp down antigovernment protests. It has also improved his international hand. By escalating and de-escalating crises in Kosovo, Vucic has positioned himself as the determiner of the region’s stability, allowing him to negotiate and bargain with countries in the West, promising to ease tensions if they meet his demands for economic support.
Such bargaining is just one of the ways that Vucic has played the United States and Europe. He has also strung the EU along as part of Serbia’s membership bid. European leaders, including Ursula von der Leyen, the president of the EU commission, say they want Serbia in the organization, and Vucic has, theoretically, agreed to accession. But he does so simply because it brings in EU aid, and what he really wants is to keep Serbia on a long and unending admission path. He does not want to join an organization that would force him to fortify the rule of law.
Many Serbs believe Russian talking points about the war in Ukraine.
In fact, as soon as Vucic came to power, he undermined all pro-Western political opposition while strengthening far-right Serbian groups to improve his own political standing. To extend his power in the region, he is also trying to keep ethnic Serbs in Kosovo in Belgrade’s orbit. And Vucic still appears interested in forcibly taking parts of Kosovo. “All Serbs know they lost Kosovo,” he stated in 2018. “But I will try everything in my might to retrieve what I can, so in the end it is not a total defeat or total loss.” With the West busy supplying Ukraine, supporting Israel, and constraining China, Vucic believes his opportunity to conduct operations in Kosovo may come soon.
To succeed, however, Vucic needs Putin’s help. He wants, first and foremost, Russian energy: Moscow’s key tool of influence. But Russia and Serbia have also bolstered their military-technical cooperation (which Belgrade has then used as a bargaining chip with the West). Vucic has even called on Moscow for domestic help. In May, for example, Vucic warned about “attempts at color revolutions”—the series of protest movements that helped topple pro-Russian rulers in post-Soviet states—and in 2021, Serbia and Russia pledged to jointly combat them. The result could be Russian meddling in Serbia’s snap parliamentary elections on December 17, which Vucic called in October.
To win those elections, Vucic will likely lean heavily on the media. It is a domain that Vucic, as Serbia’s former information minister, knows well. Under Vucic’s watch, Belgrade has spread disinformation to prepare Serbs for escalations in Kosovo, including by accusing the United Kingdom of plotting Kosovo’s war for independence, alleging that Kosovo’s prime minister has conducted acts of “terror against the Serbs,” and blaming NATO for the country’s rise in cancer rates, which Belgrade claims came as a result of NATO using depleted uranium ammunition during its 1999 intervention. Serbia’s newspapers, which largely toe the government line, are filled with anti-Kosovo narratives, and Serbian radio stations have been blasting patriotic songs. Serbian streets have been flooded with graffiti that read “Kosovo is Serbia” and “When the army returns to Kosovo.” (The latter slogan, in effect, calls for Serbia to invade Kosovo).
Vucic and Putin in Sochi, Russia, November 2021Mikhail Klimentye / Sputnik / Reuters
Russia has helped. It has put up billboards in its cities that proclaim, “We mourn together with Serbia / One color, one faith, one blood,” endorsing Serbia’s territorial claims. It has also echoed Serbian propaganda in its media outlets, which Vucic allows to freely operate in his state. These stations, such as RT and Sputnik, have used this freedom to spread pro-Russian messaging about Ukraine alongside pro-Serbian messaging—and with great success. Many Serbs believe Russian talking points about the war, and Serbia’s domestic media have adopted Kremlin narratives and spread Moscow’s propaganda. Serbian news sources, for example, frequently portray the Ukrainians as Nazis and declare, falsely, that Ukraine attacked Russia first.
For Putin, this opening has been a boon. Russia views the Balkans as Europe’s soft underbelly, and Moscow believes that Serbia is its most vulnerable spot. His goal is to turn Moscow into the Balkans’ only reliable conflict negotiator—giving the Kremlin leverage over Western powers. After all, if peace in the Balkans depends on Putin, NATO officials might have to make concessions to Moscow if they want to avoid war. By pushing the Balkans to the brink, he also hopes to show that NATO is a paper tiger and will not act if truly tested. Even if NATO does fight back against Serbia, Putin could still win. By opening another front, the West would have less capacity to help Ukraine.
The Kremlin has other reasons to support chaos in the Balkans. Putin uses the so-called Kosovo precedent to defend its illegal invasion of Ukraine, arguing that the annexation of Ukrainian territories is justified by Kosovo’s independence. According to this perverse logic, articulated by Russia’s permanent UN representative in a January speech, the illegal and wildly fraudulent annexation referendums held in occupied Ukrainian territories are akin to Kosovo’s fight for freedom from Serbia more than two decades ago. Kosovo, in other words, had the right to leave Serbia, and so the occupied Ukrainian territories have the right to join Russia. (The fact that Russia does not recognize Kosovo’s independence, or that Kosovo’s independence is, in fact, a precedent for Ukraine’s own fight for freedom, are ironies that Moscow has not addressed.)
The Kremlin’s support for Belgrade goes beyond narrow interests: Russia has a genuine ideological connection to Serbian nationalists. Putin has worked to position Russia as the leading defender of traditional cultural values—such as strict gender roles and conservative Christianity—against the liberal West. Many Serbians are natural partners. The Serbian media has accused the West of trying to destroy the Russian and Serbian Orthodox Churches, and it has railed against liberal policies, such as LGBTQ rights. Many in Serbia support the creation of the “Serbian world”—a Balkan equivalent to Putin’s “Russian world”—designed to unite all Serbs, including those in Kosovo, under a common Serbian cultural framework. Both states even have foundational myths that are rooted in the territories they would like to take. Many Russian nationalists, for their part, trace Russian civilization to a prince who governed from what is now Kyiv. Many Serbs believe their country should retake Kosovo because it is the home of many medieval Serbian Orthodox monasteries and was the site of the 1389 Battle of Kosovo, when the creation myth of Serbian civilization was born.
Western leaders understand that Vucic is motivated at least in large measure by a desire to stay in power. As a result, they have been trying to appease Serbia’s president by giving Belgrade incentives, including economic initiatives and investments, designed to stop his escalations. In June, for example, a month after ethnic Serbs injured NATO peacekeepers, the EU gave Serbia a financial grant. The U.S. ambassador to Serbia has labeled Vucic “a constructive partner,” and when Serbian armed forces participated in a multinational military exercise with NATO in June, the U.S. embassy insisted that Belgrade had chosen the West over Russia. Vucic continues to walk a tight rope in his relationship with the West. According to a leaked document, Serbia has agreed to provide ammunition to Ukraine, and Vucic has not repudiated that claim. Last March, Serbia even voted in favor of the UN resolution condemning Russia’s aggression.
But these steps are just part of Vucic’s balancing act. The military exercise has been organized in Serbia since 2014, and it requires little of Belgrade. To Vucic, ammunition shipments to Ukraine are simply a business deal, and they have not dampened Russian-Serbian relations. And the UN resolution was purely symbolic—an opportunity to boost the country in the eyes of Western leaders without jeopardizing its relations with Moscow. In fact, the resolution’s real, coded meaning was that Serbia will not give up its claims to Kosovo. “For us, Crimea is Ukraine, Donbas is Ukraine, and it will remain so,” Vucic said in January 2023. But this is only because Belgrade believes that, as the Serbian graffiti proclaim, “Kosovo is Serbia.”
If the West continues to enable Vucic, it will simply embolden him. He will keep testing NATO and trying to prove that the alliance is toothless. The West has already given him encouraging signals: after more than 30 NATO peacekeepers were injured in the May clashes with Serbian protesters, the alliance did not detain the violent protesters out of fear that doing so would escalate the conflict. But such restraint is an invitation for further escalation by Vucic, as well as by the Kremlin. Russian officials are watching what happens in Kosovo and wondering whether they can get away with attacking NATO forces and installations.
Russia has a genuine ideological connection to Serbian nationalists.
Kosovo, for its part, has at times ignored the West’s goals. For example, NATO countries have been pushing Kosovo to establish an Association of Serbian Municipalities, which Kosovo has not done so far. The West has, relatedly, accused Kosovo of forcibly installing Albanian mayors in majority Serb towns and, in doing so, raising tensions with Serbia. In response, the United States imposed measures against Kosovo and canceled the country’s participation in the Washington-led Defender Europe 2023 military exercise. But none of Kosovo’s behavior justifies Serbia’s de facto campaign to undermine its independence.
To try to contain the conflict, a week after the May attack, NATO increased its presence in the region with a new legion of roughly 500 Turkish soldiers. NATO also deployed hundreds of British troops to the country in October. But these measures are insufficient. NATO must create a coalition of the willing, headed by the United States, that can send successfully pressure Belgrade and Moscow to stop promoting political instability. That means making it clear to Vucic that, if he continues to take escalatory measures, he will face an escalating series of tangible consequences—including, possibly, sanctions.
The West is well positioned to take such steps. In June 2021, U.S. President Joe Biden signed an executive order allowing Washington to impose sanctions against anyone who destabilizes the Western Balkans. Washington should not be shy about using them against individuals who (in the words of the order) “threaten the peace, security, stability, or territorial integrity” in the region. For American sanctions to have maximum effect, the United Kingdom and the EU should join Washington’s efforts. European leaders should, at a minimum, make future assistance to Serbia dependent on specific policy shifts in Belgrade. The EU, for example, could condition further aid on Vucic’s imposing sanctions on Russia, aligning its foreign policy with that of the bloc, tamping down on regional provocations, and fulfilling the EU’s reform agenda—especially when it comes to the rule of law and media freedom.
What happens in Kosovo and Serbia rarely stays in those countries.
On the ground, NATO should deploy teams in Kosovo that counter Russia’s and Serbia’s propaganda machine. These teams should target far-right Serbian groups and remind them that Russian messaging about a “Slavic brotherhood”—to which Serbia ostensibly belongs—is a myth and that if conflict does erupt, Putin will not help them. To do so, all they need to do is speak the truth: Putin has his hands full fighting a losing war against Ukraine, and he will not provide resources to Serbia for an armed conflict with Kosovo. As evidence, these teams could point to the September war between Armenia and Azerbaijan. Russia is a longtime ally of Armenia, and yet despite Armenia’s requests, Russia provided it with no military support in the recent conflict, which Armenia lost. The teams could also remind Serbian nationalists that Moscow did not help them during the wars in the 1990s.
NATO states may not want to take these measures. In fact, they probably want to ignore Vucic altogether. The alliance has been worn thin helping Ukraine, so expending time and resources on Kosovo and Serbia may feel like too much, especially when they can just buy off the latter country’s president.
But the West must realize that, if left to fester, tensions in these states could become far more difficult—and expensive—to address. What happens in Kosovo and Serbia rarely stays in those countries, and this crisis could easily spill over to other Balkan states. Nearby North Macedonia, which belongs to NATO, might get dragged in. Further escalations in Kosovo will also invite chaos in Bosnia and Herzegovina, where Bosnian Serb leader Milorad Dodik—who has close ties to Putin—has threatened to have Bosnia’s Serbian territories secede. In October, Dodik even emphasized that Serbs should “form a single state,” consisting of Serbia, Republika Srpska, and Montenegro.
A widening conflict would be an even bigger gift for Putin, who wants the West to train its attention away from Kyiv as he fights to seize more of that country. To protect Europe and stop the Kremlin, it is therefore essential that NATO fortify its Balkans flank right now, while the costs of doing so are still cheap.