"what the US military was witnessing was not [space] debris at all, but instead a satellite with a dangerous capability"

CNN:

"This satellite has been maneuvering through geosynchronous space ... cozying up close to various communications satellites, listening to what traffic is flowing over those," said Paul Graziani, CEO of civilian satellite tracker Analytical Graphics, Inc. (AGI).

Over the course of a year, Graziani's team has watched as Luch parked itself next to three US commercial satellites and one European satellite. The Russians flew the satellite close enough to collect both civilian and, possibly, sensitive military information.

...

"We saw the approach, we saw the larger spacecraft come close to the smaller spacecraft, and then we no longer saw the smaller spacecraft," said Graziani.

The only reasonable explanation, experts say, is that the Shiyan has a robotic arm that was repeatedly grabbing and then releasing its smaller partner.