Vietnam received a fourth Varshavianka (Improved Kilo) submarine on Tuesday, as the country continues growing its submarine fleet.
Vietnam's Russian-made submarines can submerge to a depth of up to 300 meters and travel at a speed of up to 20 knots (37 kilometers per hour). The boats are unique because of their extremely quiet operation, which makes spotting them with sonar extremely difficult.
"Any power which borders the sea puts its security under threat if it doesn't have a submarine navy," Russian military expert Viktor Litovkin told Sputnik.
The Varshavianka-class submarines are used to fight both submarines and surface ships, as well as to defend naval bases, coastal and undersea communications, and reconnaissance of an opponent's communications.
"Surface ships are easy to spot with planes, drones and from space. It's practically impossible to spot a submarine with optical means of observation," Litovkin added.
The missile approaches the target at an altitude of 5 to 10 meters, which makes it almost invisible to radars and practically invulnerable to anti-missile systems.
Russia supplies Vietnam with Club-family missiles not only for submarines, but also surface ships. Club-K missiles are capable of being put on cargo vesels and from the outside look like an ordinary shipping container.
