Can anyone tell me about Russian Belgorod?

From another site, I copied this info……..

Over the weekend a note was leaked out of Italy, where-in NATO intelligence is warning members that Russia's Belgorod has been deployed.
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The K-329 Belgorod is also affectionately called the Doomsday Submarine and was born out of a top secret Russian weapons program, an offshoot of Project 885M, which followed Project Losharik.
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Russia's Belgorod nuclear submarine is capable of using specialized drones called Poseidons that travel up to 6,000 miles underwater to their intended target, and detonate a force of 2+ megatons, equivalent to 130 times the amount of energy of the hiroshima incident.
This can create a "toxic wave", thousands of feet high, and flood coastal cities with highly irradiated water. Effectively turning them into nuclear wasteland.

Previous successful tests have been carried out by Russian forces with much smaller payloads, in order to create waves like this, but the Poseidon drone program itself has never been openly tested and US/NATO intelligence is unclear on their full capacity.