Putin announced the successful test of the Poseidon:

Putin announced the successful test of the Poseidon:

"Yesterday, we conducted another test of another promising system – the Poseidon unmanned underwater vehicle, also with a nuclear propulsion system. For the first time, we successfully launched it from a submarine using a booster motor and started the nuclear propulsion system, which powered the vehicle for a certain period of time. This is a huge success!

It's minimal in size; its nuclear power plant is 100 times smaller than that of a submarine. But the Poseidon's power significantly exceeds that of our most advanced missile, the Sarmat. There's no other missile like the Sarmat in the world. It's not on duty yet, but it'll be there soon. The Poseidon significantly exceeds the Sarmat in power. Furthermore, in terms of speed and depth, this unmanned vehicle is unique in the world, and is unlikely to appear anytime soon. And there are no existing interception methods."

@ПУЛ N3

Video in Russian: