The satellites the soldiers control are overseen within a fortified command facility; if the door to the central room is left open for more than 15 seconds, an armed team will respond, as if to a foreign invasion. GPS, after all, does not only guide your Uber driver to the nearest Irish bar. It also helps U.S. cruise missiles and Predator drones alike find their way to an explosive battlefield rendezvous. It time stamps financial transactions on Wall Street. It synchronizes New York City’s traffic light system. It helps land passenger airplanes. It is worth protecting.

As Milner explains in Pinpoint, however, this functionality extends even to laughably mundane activities in the civilian realm. This includes beet farming.

Growing beets, Milner writes, requires exceptional precision: the plants are small enough that even a tiny error can throw off an entire field of seedlings, and the exact paths taken by farming equipment thus assume undue importance. To achieve the necessary level of geographic exactitude, a Colorado beet farmer named Troy Seaworth, of Seaworth Farms, doesn’t only use GPS, he tells Milner. He also relies upon a convenient but competitive back-up system: the Russian-controlled GPS rival known as the GLObal NAvigation Satellite System, or GLONASS.

GLONASS, with its own 24 satellites, was first developed in the 1970s and later launched in the 1980s as a Soviet alternative to GPS. While GLONASS has been shown to be slightly more accurate in the northern latitudes, its main advantage for global customers is simply the fact that it is not controlled by the U.S.; rather, it is controlled by the Russian military.

Farms like Seaworth’s are what Milner calls “the terrestrial end of an obsessively precise space-based positioning system.” Using a combination of GLONASS and GPS, Seaworth—as well as countless other farmers like him around the world—is able to achieve “sub-inch accuracy.” This means that an automated tractor can rumble down a highly specific route, and that individual planting, fertilizing, and watering machines can all do their jobs, without missing a beet.

If both satellite systems are not running smoothly, however, or their signals are not received in tandem by Seaworth’s machines, things begin to creep slowly but surely out of control.

Milner explained this to me over the phone with a slight laugh. He described a slow parade of agricultural equipment that almost appears drunk or, more precisely, as if they have developed the jitters. “Usually, we’re right around twelve satellites,” Seaworth explains to Milner. “If you get below six or eight, you can tell.” It is a kind of satellite withdrawal, shaky-hand syndrome for signal-addicted machines.

This odd behavior can even be the first way a farmer might notice that something has gone wrong with the satellites. In other words, even before news breaks that GLONASS is down, or that there has been a regional GPS interruption, the wobbly machines shivering out of line across a family’s beet field will betray evidence of malfunctions in the sky.