Russia is developing a massive nuclear torpedo

I seriously doubt it was an accident. I'd love to see a 100 knot submersible though. As water isn't compressible the limit on how fast you can go through it is the amount of energy you expend in displacing your mass off water around you. Now the silly picture had this thing blunt nosed, which it would not be (since that would kill efficiency), so this thing has do displace its mass in water at 51 m/sec (100 knots is 51.444 meters/second) And they claim it can do that for 10,000 km. (and the comment from the Russians is that it does this the full trip to avoid being stopped by underwater detection systems.

The only way you would have a hope of that is by using a nuclear reactor as the power plant (I haven't done the full math but just looking at random magnitudes its going to need megawatts of generating capacity) and that makes for really, really, really expensive and hard to maintain "torpedos". Further, a torpedo that moves this fast is going to cavitate (create bubbles in the water) like the Shkval-E. So this thing would be really really noisy.

So something starts screaming across the ocean toward a port city, where at 185km/h it will take 10 hours to go 1850 km, and can be stopped in its tracks by a P3-Orion with a conventional depth charge barrage?

Fun idea, but physics makes it really impractical.