The problem is, that any effort to "hide" a satellite in orbit is ultimately doomed. Turns out there is this universe-wide background of these bright dots called "stars", and these basic principles like MATH and PHYSICS. There are only certain places satellites can be. Watching those spaces to see if anything dark passes in between Earth and the distant starfield is what a LOT of amateurs spend their spare time doing. (And foreign intelligence agencies do it as well, with better tools and equipment.) So things get launched "secretly", but are quickly (1 week to 18 months later) discovered, mapped, and linked to specific launches, countries, radio frequency transmissions, etc. Space is like Kansas... big, wide open, and doesn't contain much. But there are certain people who are very interested in it, know the landscape in detail, and know when even something small changes.