A Russian satellite is stalking a U.S. spacecraft in orbit

Does anyone know what is to be gained from a technical perspective for having a satellite trail another ?

1. evesdropping ? ( physical proximity seems unneccesary ? )

2. Van Eck phreaking ? ( for potential disruption at a later time ? )

3. Kamikaze collision ? ( testing for future destructive operations ? )

4. hacking ? ( EMP, radiation induced bit-flips ? )

5. purely political ?

I dunno. Just spitballing.