Several theories have circulated as to what the "Z" symbol actually means. It first caught attention on social media after Russian tanks with "Zs" on the side were spotted en route to Ukraine.

A new tactical symbol appearing on Russian tanks and armored vehicles involved ... The most prominent marking has been the 'Z ...

Kuliak had taped the "Z" symbol -- seen on Russian tanks and military vehicles in Ukraine and embraced by supporters of the war -- to his vest for a medal ceremony at a World Cup event in March.