Relations between Serbia and Montenegro entered a new period of tension just before the European Union-Western Balkans summit in Tivat, after a security dispute involving dozens of Serbian citizens escalated into a diplomatic confrontation between the two neighboring countries.

The controversy began when Montenegrin authorities refused entry to 87 Serbian nationals who arrived on a charter flight from Belgrade. Officials in Podgorica said the group was barred from entering the country because it was assessed as posing a threat to national and internal security.

According to Montenegrin police, several of the individuals had participated in rallies supporting the Serbian government, while others were allegedly connected to incidents involving violence against anti-government protesters in Serbia. Authorities described the operation as a preventive security measure intended to eliminate any risk of disruption ahead of the regional summit.

During inspections, police reportedly discovered communication equipment, including a radio station, along with a large banner bearing the slogan "Serbia Wins," a phrase closely associated with President Aleksandar Vucic's ruling Serbian Progressive Party. Some Montenegrin media outlets subsequently referred to the group as "Vucic's informal security detail."