US becomes the first nation to publicly acknowledge weapons in orbit

Loverro's point was that the announcement added little to what anyone could already see from the ground. Most classified military satellites can be easily tracked and cataloged there, even when their missions stay secret ^[8]. His argument for saying it out loud was about who gets to describe them. "If we don't tell them what it is, they're going to hypothesize what it is," he said ^[9].

Jonathan McDowell is an astrophysicist who tracks launches and activity in orbit. He called the admission the next step in a long process ^[6]. GPS, weather and communications satellites all have military roots. As dependence on them grew, so did countries' worry about defending them, and orbit gradually became a contested war-fighting domain ^[5]. "The U.S. remains the country that is the most dependent on space assets for its operations, and to that extent, it remains the country that has the most to lose from space conflict," McDowell said ^[7].

In my view, that dependence makes the type of weapon matter more than the admission. The categories differ widely in how much harm they do to satellites nobody meant to hit. A nuclear blast in space is already banned by the 1967 UN Outer Space Treaty ^[14]. It would disable nearby satellites first. Its energetic particles would then contaminate large regions of orbit, and the dead satellites would start crashing into other objects. The result is a cascade of high-speed debris, called Kessler syndrome, that could destroy most of the satellites still working ^[15].

Jeffrey Lewis, a nuclear security expert at Stanford University, said a detonation of that kind is highly unlikely right now ^[18]. "The only reason you would do that is if you are looking at the entire space landscape and you're thinking to yourself, 'I'd like to be able to hit delete,'" he said ^[19].

Kinetic antisatellite weapons are missiles or other spacecraft that smash satellites apart. They leave less shrapnel than a nuclear blast but still enough to pose grave hazards, and Scientific American judges them possibly effective but not necessarily the most strategic choice ^[20].

The fourth category is platforms that interfere with a satellite without destroying it. For these, the magazine says the most effective results would probably come from rendezvous and proximity operations, in which one spacecraft maneuvers close to an adversary's ^[13].