Russian tanks, artillery and trucks deployed to the areas close to the Ukrainian borders sport mysterious markings, which experts say appear shortly before combat.
Videos and images of the army vehicles shared on social media show letter ‘Z’ painted on their sides, either by itself or enclosed by a white triangle, square or circle. Other symbols — such as a white triangle with two lines on either side, red triangles, white circles, white triangles and white slashes — have also been spotted on some of the vehicles, writes New York Post.
While some observers suggest the markings are identifying signals to fellow Russian troops in order to avoid being victimized by friendly fire; others have speculated that these could identify what company the vehicles are a part of, or where they are supposed to be headed in the event of an invasion.
An expert told Sky News that the painted signs are normally used to communicate where military units are headed in battle and are usually only put on equipment shortly before combat. The distinctive 'Z' in a square box appeared on a host of vehicles near the city of Belgorod in Russia, less than 30 km from the Ukrainian border and 70 km from Kharkiv, Ukraine’s second largest city.
A number of other symbols have also been seen on vehicles, including in places like Crimea.
Professor Michael Clarke, former director of the defense think-tank RUSI, said the symbols are likely to be connected to the geographic location of where the units are destined for in an offensive. He added, "The fact that they are different tells you more - they are probably signs which tell you which units are heading to the northeast or northwest of a district, for example."
Professor Clarke said the use of these types of symbols is common in war. He also said they are normally only used shortly before any fighting in case the opposing force begins to copy the markings.
During World War II, the U.S. military employed similar markings on armored vehicles and jeeps for identification purposes. American forces also used chevrons to denote different companies in Iraq.
It has not been confirmed that the markings signify where the vehicles are headed.
Another expert, Rob Lee, said in a Twitter post that these symbols were likely used to “identify different task forces or echelons.”
“The source said what the tactical signs on Russian military equipment mean: Z – Kharkiv direction [Triangle] Slavyansk, Kramatorsk [Circle] mobile reserve,” a translated version of his tweet read.
Slavyansk and Kramatorsk are located just outside the self-declared Donetsk People’s Republic and Luhansk People’s Republic, which are controlled by pro-Russian separatists.
“Most of the ‘Z’ markings seen thus far have been inside a square, but this Ural truck with a Msta-B howitzer has one inside a triangle. Possibly indicating different task forces within a larger formation or echelon. This is in Valuyki,” he tweeted, referring to a Russian city just 25 km from the Ukrainian border.