An already tense soccer match in Belgrade between the national teams of Albania and Serbia has been suspended after a drone flew over the field waving a Greater Albania flag. Based on online footage, the drone appears to be a DJI Phantom or a Phantom 2, which retails for roughly $500 to $800 depending on the model.

The Tuesday game, which was to be a Euro 2016 qualifier match between the two sides, was the first time they had met in the Serbian capital since 1967. According to The Guardian, away fans were not allowed in the stadiums in either Belgrade or in the upcoming rematch in Tirana, the capital of the Republic of Albania.

The two sides’ enthusiasm for soccer has been overshadowed by a larger political issue: Kosovo, a republic that broke away from Serbia in 2008. Kosovo, which has a majority ethnic Albanian population, is not formally recognized by Serbia but is recognized by the United States, Canada, Australia, France, the United Kingdom, and many other states.

“The supporters of Albania are not allowed to visit the stadium,” Milivoj Mirkov, head of security for the Serbian Football Federation, told The Guardian. “[The Union of European Football Associations] banned away supporters from this as well as the rematch that will be played in October 2015 due to security reasons. Every Albanian supporter that tries to attend the match will be arrested and prosecuted.”

According to the British newspaper, the drone was flown by fans outside the stadium and was brought down by Serbia's Stefan Mitrović.

That drew the ire of Albanian players, who got into a tussle with their Serbian counterparts. Eventually, according to Deadspin, “Albanian players were pelted by garbage by the hometown fans.”

According to commenters on Deadspin, many Serbian fans in attendance were chanting “Ubi ubi ubi šiptara,” which translates to “Kill Kill Kill Albanians,” a rallying cry also heard at a match in 2011 between a Serbian and an ethnic Albanian club team from neighboring Macedonia.