Tracking objects in space is something China and Russia can do just fine today, it's hard to keep the presence of a satellite a secret. But trying to determine what a satellite is doing is a bit harder. You can infer based on altitude, orbit shape, and inclination. EO birds generally fly at low altitude or in highly elliptical orbits to capture higher latitudes. ELINT and space observation birds fly near adversary satellites. Generally, satellites don't move too much so you don't need to spend a lot of resources tracking them. However, things like the X-37b and the GSSAP satellites are reported to be highly maneuverable which not only allows for flexible missions but also more difficult track and requires more resources to do so.