Russia has launched the Vietnamese Navy's fourth Varshavyanka-class submarine at a ceremony held at St Petersburg's Admiralty Shipyards, city officials have announced.
Vietnam has already acquired two of the submarines, with the third undergoing sea trials and another now under construction at St Petersburg's Admiralty Shipyards, RIA Novosti reports.
In December 2009, Vietnam's Defence Ministry awarded a $2bn contract to Russia to deliver a total of six submarines to strengthen its naval capabilities and better defend the country, as reported by the news agency.
Under the contract, Russia will also provide training for the Vietnamese submarine crews, while deliveries of the submarines are scheduled to be completed by 2016.
The Varshavyanka-class (Project 636), an improved version of the Kilo-class submarines, features advanced stealth technology, extended combat range and provides the ability to strike land, surface and underwater targets.
Designed for anti-shipping and anti-submarine missions in relatively shallow waters, the submarines can cruise underwater at a speed of 20k and have a cruising range of 400 miles.
Capable of accommodating a crew of 52, the submarines can patrol for 45 days and are armed with 18 torpedoes and eight surface-to-air missiles.
Featuring low noise, advanced hull architecture and an optimal level of control process automation, the submarines provide high reliability and require low maintenance.
Having first entered service in the early 1980s, the Russian Kilo-class submarines were designed by the Rubin Central Maritime Design Bureau.
Originally built at the Komsomolsk shipyard, developments to the vessel resulted in the current production versions, Type 877EKM and Type 636.