Group : Surveillance Ships
Status : Active
Also Known As : Meridian, Vishnya
Origin : Poland
Contractor : Northern Shipyard
Initial Operational Capability (IOC) : 1985
Total Production : 7

The Project 864, also known as the Vishnya and Meridian, is an electronic surveillance and intelligence gathering ship built by Stocznia Polnocna shipyard in Gdansk (Poland) for the Soviet Union's Navy in the 1980s. The ship's capabilities are built around the Communication Intelligence (COMINT) and Signals Intelligence (SIGINT) concepts. The Project 864 are equipped with two satellite communications antennas inside a radome. The propulsion system consists of two diesel engines developing 4,400-bhp and a top speed of 16 knots. The Project 864 weapon system is intended to counter airborne threats using two AK-630 30mm guns and two SA-N-8 surface-to-air missile systems. The Russian Navy operates seven Meridian-class vessels to be replaced by the Project 18280 intelligence ship by 2020.