Project 159A (ex-FSU Petya II)

The Project 159A, also known as the Petya II-class frigate, was a class of light frigates (often classified as corvettes) built for the Soviet Navy. Primarily designed for anti-submarine warfare (ASW), these ships featured a combination of torpedo tubes, depth charge launchers, and sonar systems.

Developed in the 1960s as an upgraded successor to the original Project 159, the Project 159A was designed to counter increasingly sophisticated NATO submarines in shallow coastal waters using improved sonar suites and twin 76.2mm AK-726 gun mounts. The class officially entered service with the Soviet Navy in 1967, with dozens of hulls constructed at the Yantar and Khabarovsk shipyards. Beyond Soviet border patrols, these vessels were widely exported to strategic allies, most notably seeing active combat with the Indian Navy during the 1971 Indo-Pakistani War. While the Russian Navy retired its last units in the late 1990s, a small number of these durable frigates continued to serve with foreign operators, such as the Vietnam People's Navy, well into the 21st century.