Impressions are used by at least 4 submarines in the Black Sea to strike caliber missiles on the territory of Ukraine, and after the death of the cruiser “Moscow” began to use submarines more often, according to British naval experts G.I. Sutton and Benjamin Pittet.

These are Russian submarines of the 877 Halibut project.
Missiles are launched from a depth of up to 50 meters, which prevents radars and satellites from effectively capturing them.

The 877 “Halibut” project (08770 sub-series) is the basic serial version of the submarine, the head ones are B-248, B-401. In addition to the 08770 series, there were 08771 or 08772 series – which differed between manufacturers.
The 877E Varshavyanka project is an export modification of the first series 877 submarine project. Delivered to the Warsaw Pact countries. It differs mainly in equipment and is not completed with an air defense missile system.
The project 877EK – submarines were not built, is the “export commercial” options adapted to tropical conditions.
The 877ECM project is the “export commercial upgraded” version of the 877 submarine project. Deliveries were made to Algeria, India, Iran and China. The hydroacoustic system MGC-400E was installed. The project was adapted to tropical operating conditions. In 1999, for the Indian Navy, the 08773 project was upgraded to the designation. Modification of equipment and weapons systems (equipped with launchers of cruise missiles Club-S). She received the Lama-ER control system, the MHK-400EM / MGK-EM hydroacoustic complex, the Palladium-M combat information management system. On the modification of the submarine the vtorulievaya group and the design are kept similar to the project 877EKM.
Project 877LPMB (B-800 “Kaluga”) – equipped with 7-blade propeller from the alloy “Aurora” having saber blades. A rescue hatch was also equipped, which allows evacuation from depths to 250 m. The equipment of the warhead-5 was reworked, the engine of an economical stroke and the main rowing motor were lower-speed. On the boat installed additional navigational equipment.

Project 877В – equipped with a water jet. The main tactical and technical characteristics similar to the project 877.
Project 877M “Paltus-M” – 8 of the latest submarines of the 877 series of projects for the Russian Navy. The body is extended by 1,2 m.
Project 877B – the project of modernization of the submarine project 877. Research and development work was carried out in the 1980-s based on the project 877M. Under this project, an experimental submarine B-90 “Sargan” was laid, which was completed later on the 20120 project.
877К / 877МК projects – modernized 877 and 877М projects. after the modernization of equipment (in particular, the combat information and control system).
The 636 project – developed by the Rubin Central Design Bureau, is an export modification of the 877М project for the Chinese Navy, the equipment has been upgraded to the 877М project type, and sound-absorbing technologies are widely used.
The 636M project is an upgraded version of the 636 project. The equipment was changed, an inertial navigation complex, a periscope having a laser rangefinder, a TV channel and a night vision channel were installed. Towed antenna communication KV and add ranges. Club-S cruise missiles with launch through torpedo tubes from a submerged position can be used. Project 06361 – modification of the submarine for the Vietnamese Navy. Project 06363 – modification of the project with the updated equipment. Armed with the Caliber missile system.
The project of a special submarine based on the 877 project is likely to be used for laying pipelines on the seabed. Perhaps, after equipping it can be used for a wide range of jobs.

Submarines of the 877 “Halibus” project as well as their modifications were delivered to:
Algeria – 2 submarines of the project 877EKM;
India – 9 submarines of the 877ECM project (8 upgraded to 08773) + 1 built on the 08773 project;
Iran – 3 submarines 877EKM;
China – 1 submarine project 636M + 2 submarine project 877EKM;
Poland – 1 submarine project 877;
Romania – 1 submarine project 877.