Russia's new nuclear attack submarine starts sea trials

Every boat in the world from fishing boats to nuclear subs have a distinctive prop signature. you can tell exactly which boat it is by just listening to the screws, reactor, hull noise etc...

Also, modern navies probably have lots of ways to track subs. hell even from space. Who says that the sub has to do all the tracking. just the stalking.

US sub tech is much less fallible than one would think. yes bad stuff happens from time to time but not enough to be incapable of tracking enemy boats almost constantly.

remember. modern navies. especially the US and UK have a lot of tech invested in those boats. subs contain some of the most advanced tech the world has concieved. It would be safe to speculate that lots of goodies and spooky stuff is hidden in those hulls that we don't even know about and won't for a long time. I honestly doubt except for those who are supposed to know, that anybody civilian, and most military even really know what subs like the parch really were capable of or what sorta tech was really hidden in there. and honestly thats the way it should be.

and yes if the NSA really wanted to they could listen in on just about every phone call in most of the world. and lots of other things. the NSA likes to stay a half step ahead of any potential bad guys. half steps not a lot but it's enough.