There are three basic scenarios for how a nuclear grade cyberattack might develop. It could start modestly, with one country’s intelligence service stealing, deleting or compromising another nation’s military data. Successive rounds of retaliation could expand the scope of the attacks and the severity of the damage to civilian life.
In another situation, a nation or a terrorist organization could unleash a massively destructive cyberattack – targeting several electricity utilities, water treatment facilities or industrial plants at once, or in combination with each other to compound the damage.
Perhaps the most concerning possibility, though, is that it might happen by mistake. On several occasions, human and mechanical errors very nearly destroyed the world during the Cold War; something analogous could happen in the software and hardware of the digital realm.
A cyberattack wouldn’t be launched from a nuclear operator’s console, like the one shown here from the decommissioned Oscar Zero site, but rather through cyberspace. A human might not even be required.