Russian Vishnya class intelligence ship Kareliya transits Japanese Strait.

According to information published by the Japanese Ministry of Defense on July 9, 2022, the Russian Vishnya class intelligence ship Kareliya was spotted near the Japanese Tsushima Strait.
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Vishnya class intelligence ship Kareliya (Picture source: Russian MoD)

The Vishnya class (NATO reporting name) (also known as the Meridian class), Soviet designation Project 864, are a group of intelligence collection ships built for the Soviet Navy in the 1980s. The ships continue in service with the Russian Navy. The Russian Navy operates seven of these ships.

They have a length of 91.5 m (300 ft 2 in), a beam of 14.6 m(47 ft 11 in), and a draught of 4.5 m (14 ft 9 in). They can reach a top speed of 16 knots and carry up a complement of 146 sailors.

The Vishnya class is powered by two diesel engines Zgoda Sulzer 12AV to displace 3,470 tons full load and is equipped with the Radar MR-212/201 and the Sonars MG-349 and MGP-303. 

These ships are large, purpose-built ships designed for signals intelligence gathering via an extensive array of sensors. The data could be transmitted to shore via satellite link antennas housed in two large radomes. The ships are armed with two AK-630 close-in weapon systems and SA-N-8 surface-to-air missile (SAM) launchers, for last resort self-defense.

A spy ship or reconnaissance vessel is a dedicated ship intended to gather intelligence, usually by means of sophisticated electronic eavesdropping. In a wider sense, any ship intended to gather information could be considered a spy ship.