“A Russian state-owned arms maker reportedly unveiled the world’s first underwater drone armed with an assault rifle that’s designed to defend naval bases from enemy divers and assault teams. ‘The drone is fitted with an underwater assault rifle. It has undergone sea trials,’ Rostec, the company behind the drone’s development, told Sputnik News at the the International Military Technical Forum ‘Army 2018.’ ‘Full-fledged trials will begin closer to the start of winter. It is a unique project since no one has so far fitted [an underwater drone] with small arms. Moreover, very few [countries] in the world have underwater automatic small arms.’ It is unclear exactly what type of assault rifle the company has placed on the drone, but The National Interest reports that Russia developed the APS underwater rifle based on the AK-74 assault rifle in the 1970s. Whether the underwater system works is difficult to independently verify.”
Source: Russia is apparently putting assault rifles on underwater drones – Business Insider