After several tests of unusual “nesting doll” satellites in low-Earth orbit, Russia is now fielding operational anti-satellite weapons with valuable US government satellites in their crosshairs, the four-star general leading US Space Command said this week.

Gen. Stephen Whiting didn’t name the system, but he was almost certainly referring to a Russian military program named Nivelir, which has launched four satellites shadowing US spy satellites owned by the National Reconnaissance Office in low-Earth orbit. After reaching orbit, the Nivelir satellites have released smaller ships to start their own maneuvers, and at least one of those lobbed a mystery object at high velocity during a test in 2020. US analysts concluded this was a projectile that could be fired at another satellite.

US officials have compared the Nivelir architecture to a Matryoshka doll, or a Russian nesting doll, with an outer shell concealing smaller, unknown figures inside.

The newest suspected Nivelir satellite was launched last May from the Plesetsk Cosmodrome in northern Russia. Its launch was precisely timed for the moment Earth’s rotation spun Plesetsk underneath the orbital plane of the NRO’s USA 338 Keyhole-class optical spy satellite. Civilian missions heading to the International Space Station launch with similarly precise timing, down to the second, to intersect with the space station’s orbital plane.