I believe that attribution is more difficult in strictly on-orbit activities. I would imagine that these weaponized satellites use radar stealth approaches similar to modern fighter aircraft. AFAIK, ground radar is basically what we have for space awareness.

I would imagine that every new intelligence-related satellite will have more sensors to be situationally aware, and make attribution possible.

If you pay attention to space-nerd podcasts like MECO, "Space Domain Awareness" is getting a lot of investment. I believe that's because we are relatively blind at the moment.

https://en.wikipedia.org/wiki/Space_domain_awareness