The Killers, an American rock band that performed in Georgia, a former Soviet state in Eastern Europe, apologized for inviting a Russian fan on stage during their performance.

A stop on the band’s European tour, which wraps up early next month, was the Black Sea Resort of Batumi on Tuesday.

It was part of what the band later described as “a longstanding tradition of inviting people to play drums” that front man Brandon Flowers welcomed a Russian drummer from the audience on stage during the concert.

Videos of Flowers saying, “I see you as my brother and my sisters,” followed by, “One of the things we have come to appreciate about being in this band is it brings people together,” elicited even sterner booing from the audience, in an apparent attempt to calm the throng.

A number of clips also depict concertgoers leaving the performance in response to Flowers’ remarks.

Georgia and neighboring Russia, which formerly occupied the transcontinental country during the rule of the Soviet Union, have a protracted and acrimonious history. After the 2008 Russian-Georgian war, some Russian-occupied areas in Georgia persisted and still do today, making up up to 20% of what was once considered Georgian territory.