The killing last weekend of a Kosovo police officer by a group of 30 or more heavily armed Serbian nationalist militants marks the most significant security incident in that country, and the western Balkans region, in more than a decade. The US ambassador to Pristina, Jeffrey M Hovenier, described the attack subsequently: “We know it was coordinated and sophisticated … The quantity of weapons suggests this was serious, with a plan to destabilise security in the region.” Kosovo’s authorities concur and are even more explicit in who they blame. Namely, Serbia’s government, and its strongman president, Aleksandar Vučić. In the hours after the day-long skirmishes between the militants and police, in which three attackers were reported to have been killed, the office of Kosovo’s prime minister, Albin Kurti, posted photographs of the large cache of seized weapons and munitions. “The perpetrators acted not alone,” he wrote, “but [with] state backing. Serbia must be held fully accountable for sponsoring terrorist violence on [Kosovo’s] territory.” Serbia, of course, denies these accusations, and responded with allegations directed at Kurti and his government for their purported persecution of Kosovo’s Serbs. Yet the Vučić government also promptly declared a day of national mourning, and regime media have glorified the dead attackers as martyrs for the Serb nationalist cause. Few analysts, though, have any doubt that Serbia played a significant role in the attack. It is claimed that the country’s territory was used as a staging area for the militants, whose leadership is known to have close ties to Vučić and his inner circle. Drone footage published by Kosovo police, for instance, appears to show that the vice-president of the primary Serb ethnic party in Kosovo, Srpska Lista, was among the attackers. Srpska Lista is widely perceived as a proxy enterprise of the Belgrade regime, while Milan Radoičić has been under US sanctions for his involvement in significant criminal activities since December 2021. He is now believed to be in hiding in Serbia. Another of the attackers was allegedly the former bodyguard of the country’s intelligence chief (who is also under US sanctions). The bigger question is how this attack could have happened in the first place. Kosovo still hosts a Nato peacekeeping force of about 4,500 troops who are closely involved in policing and intelligence-gathering in the country. They were violently attacked in May of this year by Serb nationalist crowds, leaving more than two dozen peacekeepers injured. And Kosovo’s government has warned of the growing likelihood of renewed Serb-orchestrated violence since September 2021, when Serbia deployed fighter planes along the border for the first time since the 1999 Kosovo war. The answer, alas, is not comforting. The attack is the (in)direct product of a radical reorientation of American and European policy on the Kosovo-Serbia dispute and the broader western Balkans. Since 2020, Washington and Brussels have explicitly centred the interests of Belgrade over all other neighbouring polities, in an improbable scheme to pacify the country’s nationalist leaders and pull them out of Russia’s orbit of influence. This in a country where 70% of the population backs Russia’s aggression against Ukraine. Even after the May attacks on Nato peacekeepers, for instance, the US and EU, incredibly, sanctioned Kosovo. Kurti has explicitly accused the EU’s chief regional envoy, Miroslav Lajčák, of working in concert with Serbia to pressure Pristina to give in to Belgrade’s demands. And most observers agree with him. Before Lajčák was appointed, seasoned regional experts warned against the move, citing the former Slovakia foreign minister’s historical ties to Russia. Speaking to Voice of America about this week’s attack, the former CIA analyst David Kanin likewise blamed western appeasement of Vučić for emboldening extremist elements in Serbia. A sharp course correction by the US and EU is now needed. It is evident that both the Biden administration’s policies and those of the European Commission have contributed to the most significant security crisis in the region in years. Their appeasement of Belgrade has endangered Kosovo, but also neighbouring states such as Bosnia and Montenegro, where Serb nationalist militancy, also sponsored by Serbia, is likewise the chief domestic security threat. The US and EU sanctions against Kosovo must be reversed and replaced by restrictions against the Vučić regime. Serbia’s EU accession efforts should also be frozen until Belgrade demonstrates a serious commitment to de-escalation and functional acceptance of the reality of Kosovo’s existence as an independent state. . And the five EU member states who do not yet recognise Kosovo’s sovereignty should be reproached for their role in exacerbating a major European security issue when the continent can least afford it. Until then, there can be no meaningful return to dialogue, no matter how much western diplomats will it. Jasmin Mujanović is a political scientist and the author of Hunger & Fury: The Crisis of Democracy in the Balkans and The Bosniaks: Nationhood after Genocide