The Russian sub is a result of a secret joint venture with US codenamed Red October 2. The purpose of the project was to construct a stealth sub that could hide from all know CABAL detection methods. It also has the ability to detect and track CABAL controlled subs. This is important as the goal is not destroy them anymore but rather track them down and monitor their activities.

Up to this point nuclear submarines have been preferred tool of CABAL completely hidden from all in their activities. The existence of this sub changes the entire sub-meta. If they can't know for sure they are not being followed they can't use any secret sub bases without risking revealing their location.