Key Points and Summary – Russia’s Kilo-class diesel-electric submarines, nicknamed “Black Holes” for their quiet signatures, remain the backbone of Moscow’s non-nuclear undersea fleet and a key Kalibr cruise-missile platform.
-Modern Project 636.3 Improved Kilos combine stealth, mines, torpedoes, and long-range land-attack missiles, making them a serious threat from coastal waters.
Lada-Class. Image Credit: Creative Commons.
-Ukraine now claims a new long-range “Sub Sea Baby” underwater drone struck and critically damaged a Kilo-class boat in Novorossiysk, potentially knocking out a $400–500 million asset.
-If confirmed, the attack would be a major blow to Russia’s Black Sea posture and a powerful proof of concept for cheap, expendable sea drones.
Russia’s Kilo-Class Submarines: “The Black Hole”
Russia’s Kilo-class submarine, a diesel-electric attack boat designed by the Soviet Union in the 1970s, remains a crucial asset in the Russian Navy, even if Ukraine just hit one of these subs with an underwater drone attack.
Despite being an older design, the Kilo-class has been modernized over the decades, leading to the Improved Kilo II (Project 636.3) variant introduced between 2014 and 2016. Then later, also non-nuclear multipurpose submarines, like Project 636 Varshavyanka, also known in NATO as the “Improved Kilo class of submarines in addition to Project 677 Lada.
Nicknamed “The Black Hole” for their reported stealth, the modern Project 636.3 Improved Kilos combine diesel-electric stealth with long-range Kalibr cruise missiles, torpedoes, and mines, allowing Russia to threaten both ships and land targets from littoral waters.
Kilo-Class Submarine. Image Credit: Creative Commons.
Russian Kilo-Class Submarine. Image Credit: Creative Commons.
Russia’s Kilo-class diesel-electric submarine is one of the most successful naval programs in modern history. More than 70 Kilo-class units have been built during the past 40-plus years, and more than 60 remain in service with the navies of Algeria, China, India, Iran, Myanmar, Poland, Vietnam, and Russia,” wrote USNI writer Eric Wertheim.
Ukraine Claims A Drone Hit a Kilo-Class Submarine
Ukraine has claimed that it has launched a new, previously unreported “Sub Sea Baby” underwater drone and sank a Russian Kilo-class submarine in the Novorossiysk port, according to the Security Service of Ukraine (SBU).
In a Monday press release, the SBU said “a Russian submarine of the class 636.3 ‘Varshavyanka'” was struck and “suffered critical damage and was actually put out of action.”
The modified sea drones have been given an extended range that allows them to cover over 1,500 kilometers (930 miles), a significant upgrade from their previous range of 600 miles, the SBU said in a statement shared on the Telegram messaging app.
The drones can carry up to 2,000 kilograms (4,400 pounds) of cargo and have reinforced engines and a modern navigation system.
“This was a joint operation of the 13th Main Directorate of Military Counterintelligence of the SBU and the Naval Forces of Ukraine,” the press release said.
The estimated cost of the submarine is about $400 million, rising to as much as $500 million to replace, due to the economic sanctions imposed by the West on Russia due to its invasion of Ukraine.
Russia has neither confirmed nor denied the incident nor commented on the submarine’s condition. In past cases, such as the sinking of the Moskva, Moscow has either delayed acknowledging losses in the Black Sea or outright denied Ukrainian claims, even when satellite imagery or subsequent evidence later supported Kyiv’s account.
Meet The Kilo-Class Submarines
The first submarines entered service in the early 1980s. In the following decades, construction has taken place at multiple Soviet/Russian shipyards, progressing from the 877 design in the 1980s to the lengthened 636 design in the 1990s.
The 636, often called the Improved Kilo or Kilo II submarine, incorporated a range of enhancements. The 636 submarines featured improved quieting, propulsion, and automation.
Beginning in the 2010s, the 636 was further upgraded into the current variant, the Kilo Project 636.3, also known as the Improved Kilo II. The design proved popular when the follow-on Lada-class submarine (Project 677) suffered delays and failed to meet expectations.
The Kilo’s design displaces roughly 2,350 tons surfaced and 3,100 tons submerged, though some sources place the figure as high as 3,950 tons.
Kilo II submarines are 242 feet long with a 32.5-foot beam and 20-foot draft. They are powered by two diesel generators with a single seven-bladed fixed-pitch propeller. This provides a top speed of 17 knots surfaced or 20 knots submerged. The submarines have a 45-day endurance and operate with a crew of 52. Maximum diving depth has been reported as 984 feet.
The improved sonar systems have reduced the number of operators needed by automating operations from a single console.
Anechoic tiles are fitted to absorb sound waves from the active sonar, reducing and distorting return signals. These tiles also help lessen the sounds emitted by the submarine, thereby extending the range at which the sub may be detected by passive sonar.
Because they are diesel subs, Kilo-class boats have a short endurance of about 45 days. They must surface or snorkel to recharge batteries. Kilo-class boats have a range of only 400 miles submerged and 7,500 miles while snorkeling.
However, thanks to its quiet internal machinery, vibration- and noise-isolation systems, and anti-acoustic rubber coating on the outer hull, the Kilo class remains entirely capable of slipping past modern detection systems.
Kilo-Class Submarine’s Armaments
Kilo-class submarines are fitted with six 21-inch bow torpedo tubes that can launch missiles, torpedoes, or naval mines.
Many Kilo-class submarines have been outfitted to launch Kalibr missiles from their torpedo tubes for long-range land attack or anti-ship operations. The submarines have space to carry a maximum of 18 torpedoes or 24 naval mines.
Only four Kalibr missiles can be carried as part of the Kilo armament mix. The Russians have used the Kalibr missiles to attack Ukraine, which is why the reported sinking of the submarine, if true, is essential.
About the Author: Steve Balestrieri
Steve Balestrieri is a National Security Columnist. He served as a US Army Special Forces NCO and Warrant Officer. In addition to writing on defense, he covers the NFL for PatsFans.com and is a member of the Pro Football Writers of America (PFWA). His work was regularly featured in many military publications.
