Don’t know exactly what technology the Ruskies will use, but back in the ‘90s I read a story about an Australian Scientist who figured out a way to see through the oceans at any depth using special light filters or some such. The implications for ASW were obvious....Never heard about that scientist or his invention since.
Kaman Aerospace came up with a system called Magic Lantern in the early 90’s, using lasers for mine detection. Tracking a maneuvering submarine at depth from space would be quite an accomplishment.