Police in Greece clashed late Wednesday with Communist-backed demonstrators who tried to prevent a concert by U.S. military cadets.

The violent protest occurred in the central Greek city of Larissa ahead of a concert by members of the West Point Glee Club, a musical group of the U.S. Military Academy which is currently on tour in Greece.

Videos and photos shared on social media show police firing tear gas to hold back the demonstrators outside a municipal theater, while officers also clashed…