Key Points and Summary: Russia’s Sierra II-class submarines, built with titanium hulls, offer both underwater speed and stealth, posing a serious challenge to NATO submarine hunters.
-Titanium construction enhances their ability to dive deeper and remain quieter, though it’s exceedingly expensive and complex to produce.
-Only two Sierra II boats—Nizhniy Novgorod and Pskov—ultimately entered service, each armed with a variety of cruise missiles and torpedoes for anti-ship or anti-submarine missions.
-Although the Russian Navy rarely discloses detailed deployments, the Sierra II subs frequently patrol the Arctic with speed upwards of 36 knots.
-Modernization efforts could keep these titanium-hulled hunter-killers operational well into the 2030s.
Titanium Hulls and High Stakes: Meet Russia’s Sierra II-Class Fleet
One thing you can depend on when analyzing the Russian navy is the success of its submarine force over the decades.
The Kremlin and admirals in the maritime branch have always made subs the mainstay of the nuclear triad. They have given the United States and its allies fits when it comes to counteracting the swift and silent submarines, especially when it comes to protecting those powerful doomsday “boomer” subs that can launch nuclear missiles.
The Sierra II-class is one group of boats that need more light shined on them to determine their advantages over adversarial submarines from the United States and NATO.
Why Titanium is Great in Undersea Warfare
The Sierra I and Sierra II submarines have titanium hulls. The Russian Navy loves its titanium-hulled boats.
Titanium has better durability with a lighter weight. This helps improve speed and maneuverability in the depths of the sea.
The Sierra IIs are also known for their stealth and deathly quiet. Plus, they have better protection against torpedoes and the ability to dive deeper.
However, titanium hulls are not easy to make. They are expensive and create complex manufacturing processes. The Sierra II-class has only one nuclear reactor, a concept executed in the design of the earlier Charlie-class fast attack submarines.
The End of the Cold War Was a Difficult Time for Sub-Building
In 1990, the Sierra II-class Nizhniy Novgorod was built. This was followed by the Pskov in 1993. It was not a good time for Russian subbuilders.
The Cold War had ended, and the Soviet Union fell apart. Money and resources were scarce, and the future of the navy was in question.
However, the Russians did not give up, knowing that they needed fast and stealthy boats to ensure that the military could survive with strength.
The Sierra II-class emphatically put the word “attack” in the fast attack class of subs. They have a wide variety of weapons that could damage or destroy enemy shipping.
The Sierra II-class can “fire P-100 Oniks anti-ship cruise missiles, the Type 96R Vodopad and RPK-6 Vodopad anti-ship cruise missiles, as well as the powerful Type 40 torpedoes,” according to BulgarianMilitary.com.
Sierra II-Class Submarines: Search and Destroy Ability
The Sierra II-class are hunter-killers. They guard the Motherland from close-in shipping attacks. They can sniff out enemy submarines, especially the boomers from the United States. The anti-ship missiles are powerful and can travel undetected for long periods under nuclear power. The Sierra II-class boats are fast and can reach 36 knots when submerged.
The Nizhniy Novgorod and the Pskov are still operational in the Northern Fleet. That means patrolling the Arctic and keeping the water safe in that region.

Sierra-class Submarine.
Titanium Hulls Are Tricky to Produce
The Russians could have built more of the Sierra II-class, but they were so challenging to make that the navy reconsidered.
The National Interest explained what must happen to make the subs a reality. “To successfully weld huge titanium panels on a large scale, Soviet engineers had to first create enormous warehouses that were hermetically sealed and then filled with argon, an inert gas that would not interfere with the welding process. Welders had to wear a large cosmonaut-like suit that would supply them with oxygen while inside these warehouses.”
Secretive Nature of the Sierra II-class
The Russian navy keeps the Sierra II-class secret. Vladimir Putin does not brag about the boats. The state-run media outlets rarely reveal naval exercises; when they do, the reports are often vague. One consisted of a torpedo exercise that the Nizhniy Novgorod and the Pskov embarked on in 2019.
Russia is expected to modernize the Sierra II-class boats this decade. They may be able to serve throughout the 2030s.
The Nizhniy Novgorod and the Pskov could be redeployed into the Atlantic or Black Sea.
However, Russia has designs on the Arctic, and the Sierra II class will play a large part in the strategy and operations in the frigid waters of that region.

Sierra-Class Submarine. Image Credit: Creative Commons.
The titanium hulls give the subs many advantages despite the difficulty of producing and the expensive process. The titanium subs are deep-diving and quiet. Their cruise missiles and torpedoes can surely take out enemy shipping should a conflict with Russia ever arise. They rarely, if ever, surface in a way that arouses media coverage.
The Sierra II-class are challenging to track, and it will be interesting to see how long they stay in the Arctic or if they can sail in the Black Sea to help in the war against Ukraine.
About the Author: Brent M. Eastwood
Brent M. Eastwood, PhD, is the author of Don’t Turn Your Back On the World: a Conservative Foreign Policy and Humans, Machines, and Data: Future Trends in Warfare, plus two other books. Brent was the founder and CEO of a tech firm that predicted world events using artificial intelligence. He served as a legislative fellow for U.S. Senator Tim Scott and advised the senator on defense and foreign policy issues. He has taught at American University, George Washington University, and George Mason University. Brent is a former U.S. Army Infantry officer. He can be followed on X @BMEastwood.

T zM
January 15, 2025 at 11:02 am
The pressure hull will transmit more energy to the inside of the sub from a torpedo explosion. The pressure hull might not rupture (as in the case of a steel hull) but that energy transfered to the interior will still damage equipment and sailors. This might result in a soft kill where the sub is out of action until critical systems are repaired, if they can be repaired at sea … during this time the sub is more vulnerable to attack ….
Carrington Ward
January 15, 2025 at 11:10 am
This article sounded better in the original Russian.
Unbelievable the degree to which Russophile flacks have infiltrated US policy apparatus and policy commentariat.