There was no financial profit to be gleaned from turning off the power. It was a political hit job. In the months that followed, security researchers confirmed as much. They traced the attack back to a well-known Russian intelligence unit and made their motives known. The attack was designed to remind Ukrainians that their government was weak, that Russia was strong that Putin’s digital forces were so deep into Ukraine’s every digital nook and cranny that Russia could turn the lights off at will. And just in case that message wasn’t clear, the same Russian hackers followed up one year later, turning off Ukraine’s power again in December 2016. Only this time they shut off heat and power to the nation’s heart—Kyiv—in a display of nerve and skill that made even Russia’s counterparts at the National Security Agency headquarters in Fort Meade, Maryland, wince.

–This is How They Tell Me The World Ends: The Cyberweapons Arms Race, Nicole Perlroth