Russia has reportedly begun equipping some of its tankers with mounted weapons in an apparent effort to deter potential boarding attempts by NATO member states.

Two fixed guns were observed on the bridge of the Marshal Vasilevsky, a tanker used to transport Russian liquefied natural gas (LNG), The Caspian Post reports via The Times.

Security analysts believe the weapons may have been installed to defend against drone attacks and possible boarding operations.

Patrick Bolder, an expert at the Hague Centre for Strategic Studies, said that the move could serve as a warning to NATO against attempting to seize Russian vessels, saying such actions could risk escalating into a broader military confrontation.

If claims of armed vessels within Russia's so-called "shadow fleet" are confirmed, European countries would likely become more cautious about conducting interception or seizure operations at sea.