The ‘Poseidon’ Underwater Drone: Russia’s New Superweapon to Beat Ballistic Missile Defense?

Russian President Vladimir Putin first publicly announced in March 2018 during his annual State of the Nation address that the Russian defense industry was working on a nuclear-propelled, intercontinental-range, nuclear-capable underwater drone, designated Poseidon. The drone is reportedly designed to deliver a 2-megaton nuclear warhead to destroy naval bases, carrier strike groups, and entire coastal cities by triggering a radioactive tsunami wave.

Ever since the Russian president’s announcement, there have been wildly disparate and highly speculative accounts about the new weapon system’s purpose and capabilities. This article seeks to summarize what we know about the Poseidon, alternatively referred to as an unmanned underwater vehicle (UUV), autonomous underwater vehicle (AUV), or simply an intercontinental-range, nuclear autonomous torpedo.

The existence of the Poseidon program was first revealed in November 2015 when a Russian state-run television station aired footage showing a classified presentation slide of the purported nuclear-powered weapon system.  The inception of the program dates back at least two decades. However, the original idea of creating nuclear-powered intercontinental-range torpedoes goes back all the way to the 1950s. The Soviet Union conducted a number of experiments but eventually abandoned the idea of building such an underwater weapon as it was considered both impractical and unreliable at the time. 

While there has been some speculation about whether the program even exists, there are a number of indications that the Poseidon is indeed real. First, the 2018 U.S. Nuclear Posture Review (NPR) cites the “Status-6 AUV” – later in 2018 the Russian Ministry of Defense renamed it “Poseidon” – as a nuclear delivery platform that already had undergone tests. In other words, the Pentagon believes that the Poseidon exists. The Poseidon is also listed in Russia’s state armament program for 2018-2027, which notes that the new weapon is expected to be delivered to the Russian military in the late 2020s. 

Second, Russia has built the B-90 Sarov-class Project 20120 diesel-electric submarine to carry a Poseidon-sized torpedo or UUV. Based on open source intelligence estimates, the sub has a 24-meter long forward facing hangar that would be capable of accommodating the Poseidon. (The Poseidon has a diameter of two meters and is over 20 meters long.)  Russia would likely not spend time and money on building such an underwater platform were it not for the specific purpose of testing a massive torpedo or new UUV.

Third, Russia is also the process of converting two nuclear-powered subs to carry large torpedoes or UUVs: the Project 09852 sub – based on the 949A Oscar II-class nuclear-powered guided missile submarine – and the Project 09851 submarine – reportedly a downsized variant of the Borei-class of nuclear-powered boomers. The two subs were laid down in December 2012 and July 2014 respectively at the Sevmash shipyard. 

What are the Poseidon’s likely capabilities? The 2015 slide referenced the Poseidon as a “self-propelled underwater vehicle” with an operational range of “up to 10,000 kilometers” and capable of operating in depths of “up to 1,000 meters.” The slide also states that the Poseidon uses pump jet propulsion. According to Russian military sources, this would enable the torpedo to travel inside a bubble of gas to reduce friction using the same supercavitating technology as Russia’s most advanced high-speed torpedoes, achieving a top speed of over 100 knots or over twice the speed of the fastest U.S. torpedo. However, according to naval analyst H.I. Hutton, the Poseidon lacks the proper propulsion system and design to be supercavitating. Consequently, a speed of 50 or 70 knots, as cited by other Russian defense industry sources, appears to be more realistic.

Based on the 2015 slide, the Poseidon can be fitted with a thermonuclear warhead with a layer of cobalt-59 yielding 100 megatons. However, more recent reports cite a 2 megaton warhead. The different warhead yields, though, may not matter that much when it comes to creating giant waves out at sea. As David Hambling pointed out in a recent article, the U.S. military looked into the effects of nuclear weapons blasts in the oceans in the past, concluding in a 1973 analysis that “most wave energy is dissipated by breaking on the continental shelf before reaching shore.” This phenomenon, known as the Van Dorn effect, has been confirmed by later studies. Therefore, the primary danger posed by the Poseidon remains its thermonuclear blast. 

It remains unclear whether the Poseidon is an UUV, AUV, or a long-range torpedo. Put otherwise, it remains uncertain whether the Poseidon serves only as a nuclear-warhead delivery platform or could be used for other purposes including intelligence, surveillance, and reconnaissance (ISR) missions. What is clear, however, is that should the Poseidon ever become an operationally deployed system – the Russian Navy is expected to deploy over 30 Poseidons, according to a Russian defense industry source – it will serve as a weapon of last resort to strengthen Russia’s nuclear deterrence posture vis-à-vis the United States and NATO amid increasing sophisticated ballistic missile defenses.

The need for such a new weapon system has likely become even more acute in the eyes of Russian policymakers following the recent release of the Missile Defense Review, a congressionally mandated statement of U.S. policy to defend the United States and its allies against missile attacks, which places new emphasis on defense against Chinese and Russian regional missile capabilities. Accordingly, the Poseidon is bound to stay in the news for the foreseeable future.