Via an article in the Inquirer and the original Space.com article, the French military is threatening to publish US spy satellite orbital data, which has been left out of the official US catalog of orbiting objects. Amateur satellite observers find this stupid and just figure out the orbits themselves. What the French really want is a quid pro quo agreement to not publish French spy satellite orbits. But of course, all it takes are a couple of people with clocks watching the sky to figure the orbit, so why hide the orbit elements in the first place?
The French discovered these uncataloged satellites via radar returns. The US has a fence of VHF radars across the southern US, known as NAVSPASPUR, that can detect nearly every satellite in LEO orbit over a short time period. Amateurs can pick up the radar returns from meteors and other objects from these transmitters.