Back in 2018, we posted “Status-6 — Putin’s Autonomous “Doomsday” Torpedo.” It described a huge new torpedo, initially called Status-6 by the Russians but now known as Poseidon, and dubbed Kanyon by the CIA, a 65′ long, autonomous nuclear-powered and nuclear-armed underwater vehicle able to deliver a thermonuclear cobalt bomb of up to 100 megatonnes. It is said to have a top speed of 100 km/h (54 kn), with a range of 10,000 km (5,400 NM.)  Russian Oscar Class submarines are said to be capable of carrying up to four of the torpedoes secured externally. We also noted that some experts doubted that the weapon was being developed while others claim that it had already being tested in the Arctic.

Recent satellite images of the Russian naval shipyard at Severodvinsk show that the Poseidon is very real and beginning to be tested.

H I Sutton writing in USNI News notes that Poseidon represents a new category of strategic weapons and changes the shape of the nuclear threat. Although the specifications of the system are obscured by secrecy, guesstimates and misinformation, the new weapon is expected to run extremely deep and fast, based on suppositions from the design.

The system will be carried by a fleet of new host submarines designed to field the submarines. The first of these, K-329 Belgorod, is currently based just across the river from the new pier. The submarine is undergoing sea trials and is currently rigged for sonar calibration. A second Poseidon-carrying submarine, Khabarovsk, is under construction nearby. Ultimately four Poseidon submarines are expected to be built, with operational patrols starting in the coming years.

There is still considerable debate, however, about how and even if the massive torpedos will ever be used.

One possible use of the torpedo would be to destroy coastal cities by detonating its warhead offshore, creating a massive radioactive tsunami. Skeptics aren’t convinced. Michael Peck, writing in National Interest comments that that leaves the question of why Russia would choose to nuke an American city with an underwater drone – even one that allegedly travels 100 miles an hour – when an ICBM can do the job in 30 minutes.

Peck also notes that more intriguing is the suggestion that Poseidon could be used against U.S. aircraft carriers. A very fast, nuclear-armed drone could prove difficult for American anti-submarine defenses to stop.

If the goal is to sink a U.S. carrier, couldn’t Russia saturate a carrier’s defenses with a volley of conventionally-armed hypersonic missiles like the Mach 5-plus Khinzal? And if nukes are being used, Russia has no shortage of missiles, bombs and aircraft to target American ships.

Peck concludes that whether Poseidon adds much to Russia’s strategic nuclear forces is doubtful. No less is doubtful is Poseidon the Carrier-Killer.

On the other, Lieutenant Commander Joshua M. M. Portzer argues that the ramifications of the Poseidon system cannot be overstated. He suggests that as the torpedo is not covered by existing arms control treaties, its existence gives the Russians a potential strategic advantage. The Poseidon is impervious to ballistic-missile defense because it travels by and detonates in the ocean. There is no option to detect a Russian launch of this weapon and then execute a counter launch. The United States would not know of the threat until it had detonated.

Portzer writes, consider an underwater nuclear attack against Naval Station Norfolk. Is a U.S. threat of a second strike credible? What if Russia denies the attack? Would Washington pull the trigger in the face of public Russian denial? And what of primacy? An attack on Norfolk would not destroy the U.S. nuclear arsenal; the United States could still volley a second strike. However, Poseidon is essentially undetectable. In terms of capabilities, then, the United States no longer holds primacy in nuclear weapons (or even parity).  A coordinated attack against both Norfolk and San Diego ports would catastrophically cripple the Navy. 

Whoever may be right, the continued development and testing of Poseidon is troubling.