my guess is that, by now, in 2025, with 50 years of classified electronic signature (radar/sonar) research, above and below sea level, our effective sonar range, which is 'officially' less than the russian boats, is not really important any more because, and i'm just speculating here, i would be surprised if we did not have an ultra-classified technology that functions as an undetectable non-stationary "dew line" deployed near the ocean floor across the bering straight, key ('northwest passage') chokepoints in the high canadian arctic and norway-svalbard-greenland, and then 'similar' if not the same technology with the ability to run 'forever' on nuclear power, shadowing every russian boat on every patrol anywhere it goes anywhere on the planet
in other words, we probably know where the russian boats are 7x24x365; china too (they have 6 w/ nukes)