So how could this happen? For many reasons. In part, it’s because emergency systems have long decoupled from the threat of war in general, let alone global thermonuclear war specifically, even as they’ve become incredibly robust at sending peacetime messages. In part, it’s because media have splintered and fragmented, making it hard to get detailed official messages to everyone. In part, though, it’s because media have consolidated in devices everyone holds in their hands and pockets, but which work best with small quantities of narrow-bandwidth information. And, in part, it’s because someone pressed the wrong button on a computer, which then did exactly what it was programmed to do.