Inside Russia’s $400M stealth sub: specs, missile load, and how Ukraine blew it out of action

NV explains what is known about these submarines.

The Varshavyanka project (NATO codification — Improved Kilo) was developed in the late 1970s and is considered highly successful by the Kremlin. That is why construction of the series, with a number of upgrades, continues to this day. Nearly all Project 636 submarines have been built or are being built at the Admiralty Shipyards in St. Petersburg.

The aggressor state’s navy also operates Varshavyanka submarines of Project 636.3, which differ somewhat from the base Project 636 and 636.1 models that were exported to China, Algeria and Vietnam.

According to Russian propagandists at TASS, since 1996 China has received 10 submarines of this type, Algeria two, and Vietnam four.

Varshavyanka submarines are 74 meters long, can dive to depths of up to 300 meters, and are equipped with a double hull divided into six compartments.

They are armed with Kalibr cruise missiles, naval torpedoes, as well as Igla‑1 and Verba man‑portable air defense systems. Under standard staffing, the submarine’s crew consists of 12 officers and 40 sailors. Russian sources claim Varshavyankas are among the quietest submarines in the world and do not need to fully surface to recharge their batteries.

The submarine’s underwater range is listed as follows:

• 400 miles at three knots;
• 7,500 nautical miles when operating its engine underwater at a speed of seven knots (about 13 km/h);
• endurance of 45 days.

In 2024, the commander of Group 13, a special unit of Ukraine’s HUR Defense Ministry, call sign Thirteenth, told Krym.Realii in an interview about plans to destroy a Russian Varshavyanka submarine using maritime drones.

“Yes, we’ll do it — just a little later. It doesn’t spend its entire life underwater. It also moves on the surface. We’ll simply catch it. We couldn’t catch the Kotov (the Russian Black Sea Fleet patrol ship Sergey Kotov — ed.), but we did. This just requires more time, careful preparation and maybe a bit of luck,” the officer said.

The SBU press service reported on Dec. 15 that as a result of a unique special operation in the port of Novorossiysk, Sub Sea Baby underwater drones detonated a Russian Project 636.3 Varshavyanka‑class submarine.

Ukraine’s security services said the explosion caused critical damage to the submarine, effectively putting it out of action.

According to the SBU, the submarine was carrying four launchers for Kalibr cruise missiles, which Russia uses to strike targets in Ukraine.

“The cost of a Varshavyanka‑class submarine is about $400 million. Given international sanctions, building an аналогous submarine today could cost up to $500 million. This class of submarines is also known as the ‘Black Hole’ because its hull absorbs sound and remains difficult for sonar systems to detect,” Ukrainian officers said.

There are also reports that the Varshavyanka submarine blown up by the SBU on Dec. 15 had been relocated to the port of Novorossiysk after Ukraine’s Armed Forces attacked a submarine of the same class — but Project 877/636, Rostov‑on‑Don — in the port of Sevastopol in September 2023.