The Russian military used the identifying mark to reduce friendly fire ahead of the special military operation, helping to distinguish Russian vehicles from Ukrainian ones. "Z" is the Russian word for west (запад) that designates the Western Military District or west-bound infantry.
The most popular theory among military experts is that these symbols are used to designate location – either where they are stationed or where they are headed. Z could potentially stand for zapad, meaning west.
Professor Michael Clarke, former director of the defence think tank Rusi, told Sky News: “Often these symbols will be location based – they will be communicating where a unit is heading. If they were only to mark the vehicles as being Russian, you could just use one symbol.
Various symbols have been spotted on Russian vehicles - with many displaying the letter 'Z'
inews.co.uk