Oh, for Pete's sake. From the discussion here, one would think the Russians never heard of the Roman or Greek alphabets. Of course, most Americans don't know anything about the Greek or Cyrillic alphabets---but we wallow in ignorance. A "Z" is a good, recognizable ROMAN alphabetic character, distinct from any Cyrillic character---which makes for good recognition. These are recognition signals to prevent friendly fire accidents. They correspond to the "invasion stripes" that were painted on Allied pursuit planes during the Normandy invasion, to prevent confusion with German pursuit planes. Things get very mixed up when combat is face-to-face.