 As well as this, twenty Project 357 ("Libau" class) despatch vessels were built on the same hull, but were lightly armed.The ships served in 1950s–1960s on all Soviet fleets and flotillas in the Baltic Sea, Black Sea, Caspian Sea, Arctic Ocean and Pacific Ocean as part of Soviet coastal anti-submarine defences.Ships were also given to the Soviet Border Guards and were used actively as border patrol ships.