Russian state news agency TASS reported on 29 October 2025 that President Vladimir Putin announced the successful test of the nuclear-powered unmanned underwater vehicle (UUV) known as Poseidon. According to TASS, the unmanned submarine was launched from a carrier submarine and operated its onboard nuclear power unit during an autonomous voyage.
For his part, Russian president Putin is reported to have described Poseidon’s destructive power as surpassing that of the Sarmat ballistic missile and to have asserted that there are no effective means to intercept it. Russian press coverage characterised the trial as a demonstration of technical integration rather than a nuclear detonation.
Analysts, however, warned of the far-reaching strategic consequences that any use of a nuclear-armed system would entail — including the devastation of ports and critical infrastructure, substantial loss of life, and the almost certain prospect of retaliatory strikes.
They also note that Poseidon would further bolster Russia’s second-strike capabilities and intensify international pressure to improve seabed monitoring and harbour-defence systems.
