The KOR-2 (Be-4) is a ship-based reconnaissance flying boat developed in the 1930 by the Beriev Design Bureau for the USSR Navy for new ships of the "Grand Sea and Ocean Fleet". The KOR-1, already in service, did not suit the fleet due to its flight characteristics and slow production rate of 12 aircraft in two years. At the end of 1938, the task of designing the KOR-2 was assigned, and in addition to the Joint Design Bureau of Marine Aircraft Engineering (OKB MS), headed by Beriev, other designers submitted their projects as well. However, in February 1939, the task was transferred directly to the OKB MS. Despite exceeding the specified dimensions in the preliminary design, it was accepted. The first mock-up was ready on January 21, 1940.

Production was to be carried out at Plant No. 288 in Savelovo, where the first aircraft was assembled by August 11, 1941. The second aircraft was ready on September 20. After that, the factory evacuated to Omsk, where nine more aircraft were produced over the next two years. In 1944, production of the KOR-2 was transferred to Plant No. 477 in Krasnoyarsk. Over the next two years, 38 aircraft of this type were produced there. These aircraft were primarily used in the Black Sea for coastal reconnaissance, escorting convoys, and anti-submarine defense. They were also used as catapult reconnaissance aircraft on Project 26 cruisers. The same model was to be used on Project 23 battleships, as well as Project 69 and 69I cruisers.

The KOR-2 was introduced in Update 2.49 "Tusk Force", as a catapult reconnaissance aircraft for Soviet ships. It has weak defensive armament consisting of only one 7.62mm ShKAS machine gun, as well as mediocre offensive armament consisting of one additional ShKAS machine gun. However, it can carry two 100-kilogram bombs, making it dangerous for some small fleet boats.