Montenegro has emerged as the clear frontrunner in the EU accession race, but its path to membership is increasingly complicated by interference from neighbouring Serbia. Officials, diplomats and analysts say Belgrade is quietly working to destabilise Montenegro, leaving Brussels to navigate a delicate balancing act between two candidate countries with intertwined histories.
While Montenegro advances through the negotiation process, Serbia's own bid has stalled. Belgrade has yet to open all negotiation clusters, and a recent attempt was blocked by eight member states. This disparity has fuelled concerns that Serbia may try to slow Montenegro's progress to protect its regional influence and avoid uncomfortable comparisons.
Serbian interference in Montenegrin affairs
MEP Tonino Picula (Croatia/S&D) told journalists before the July plenary vote on the annual progress report that "we see some actions by the [Serbian] government and opposition parties that complicate the internal situation in Montenegro." Three officials from the European Commission and national governments confirmed they were aware of these attempts, describing them as a unique complication for the EU.
Jovana Marović, a former Montenegrin deputy prime minister, said: "Serbia is doing whatever it can to shape Montenegro from the inside, influencing what we are as a country." She pointed to initiatives such as a proposal to elevate Serbian to an official language alongside Montenegrin in the constitution, and a halted attempt to rename Podgorica's National Library, which honours anti-fascist Radosav Ljumović, after Marko Miljanov, a figure tied to the Montenegrin-Serb tradition.
Marović sees a pattern: "Serbia is systematically trying to create ethnic divisions." She also cited municipal-level efforts by pro-Serb parties to annul Montenegro's recognition of Kosovo. Despite these pressures, she stressed that the accession process has not been derailed. In July, 74 of 77 lawmakers voted to open constitutional reform, and in late August, amendments were adopted with a two-thirds majority of 68 votes.
Historical tensions and regional rivalry
The relationship between Montenegro and Serbia is steeped in history. Montenegro gained sovereignty at the Congress of Berlin in 1878, lost it to Serbia, and regained independence in 2006. In May, Serbian President Aleksandar Vučić dismissed Montenegro's 20th anniversary of independence as "a glamorous celebration of secession from my Serbia," saying attendance would be "a spit in the face" for Serbs. The following month, he attended the EU-Western Balkans Summit in Tivat, citing security concerns over a possible assassination plot.
Florian Bieber, coordinator of the Balkans in Europe Policy Advisory Group, said: "Relations between Serbia and Montenegro have declined in recent months. Serbia might want to be a spoiler for Montenegro's accession process." He added that "Montenegro joining the EU creates uncomfortable questions for Serbia."
According to the Polish Centre for Eastern Studies, Belgrade could try to destabilise Montenegro to derail its EU bid, as Montenegrin membership would undermine Serbia's regional leadership and weaken its influence in Podgorica. Roughly a third of Montenegro's citizens are ethnic Serbs, and Belgrade maintains influence through aligned politicians, media, and the Serbian Orthodox Church.
Serbia's Ambassador to the EU, Danijel Apostolović, denied any interference: "Serbia has no interest in interfering with Montenegro's EU accession process. Our focus is on our own reform process and economic growth." He lamented the lack of strategic decisions by some EU member states, noting that the European Commission has recommended opening Cluster 3 five times without success.
Brussels' dilemma
The deteriorating relationship between Serbia and Montenegro poses a unique challenge for Brussels. Podgorica is closest to joining, while Belgrade is seen as the most influential country in the Western Balkans. The Commission's recent push to revive Serbia's accession was driven by member states that consider Belgrade too important to leave behind. Some may link Ukraine's bid to progress on Serbia, to maintain geographical balance.
For Belgrade, the process is not merit-based but geopolitical. It points to Montenegro's alleged rule-of-law shortcomings, including the presence of powerful criminal clans, and notes that Montenegro does not recognise Serbian as an official language, while Serbia recognises minority languages. Podgorica, by contrast, credits its inclusive approach for its reform progress.
As Montenegro edges closer to membership, the question is whether Serbia will accept the outcome or continue to undermine it. The EU's response will shape not only the Western Balkans' future but also the credibility of its enlargement policy. For now, Montenegro's political elite remains united, but the pressure from Belgrade shows no sign of abating.
