It is non-trivial to create what amounts to an invisible satellite.
It has and continues to be done not only by the US, but by other countries as well.
Techniques are continuously developed and refined to see such "invisible" satellites. It's just another arms race.
Secondly, I would imagine that the trajectories of all satellites are available to all agencies that launch stuff into space.
There are certain satellites that are not tracked except by the agencies that use them, and by anyone else who happens to notice it. There are public lists of all known satellites.
But within weeks after MISTY's shuttle deployment, both U.S. and Soviet sources reported that the satellite malfunctioned. Richelson explained that a spacecraft explosion "may have been a tactic to deceive those monitoring the satellite or may have been the result of the jettisoning of operational debris."
Whatever the case -- and to the chagrin of spysat operators -- a network of civilian space sleuths had been monitoring a set of MISTY maneuvers and the explosion, ostensibly part of a "disappearing act" meant to disguise its true whereabouts.
So check it out yourself. My understanding is that amateur satellite trackers have found and verified numerous unpublished satellites. They feel they are doing a service - "If I can see and track it with my limited resources, you can bet China, etc know about it years ago."
Imaging a soyuz crashing into one of those massive spy satellites with a relative velocity of several kilometers per second...
Check out Big Sky Theory. You'll find that the amount of 3-D space is so large in volume that even satellites meant to hit each other (for various tests) are extraordinarily difficult to target. When satellites start to accidently crash - it is greater then 99.9% certain it was not random or accidental, statistically speaking.
I just can't see how the US could not have spy satellites that are difficult to see and unpublished. The article mentions well-known satellites (keyhole). It will be news (well, actually no one will know publicly) when the chinese test their laser against all our unpublished satellites.
Like others have said, this is likely a story to get greater funding (Congress is going to start dealing with budget soon) for the various agencies. It looks like it may have been done well - a single statement in a long report, and no official statements other than that. Congresspersons, start your engines! China's going to attack Tiawan, and before we find out it'll all be over! Better throw a few more protected satellites up! China's hindering the Iran peace process to keep us occupied in other parts of the world! That might destroy Walmart's business model and we'll lose 1000's of jobs in our state! etc, etc, etc.