In December 2015, Russian hackers allegedly pummeled Ukraine’s power grid, disrupting the flow of electricity for nearly a quarter-million Ukrainians. Then, in December 2016, roughly a year after the first attack, the hackers struck again. But this time, they targeted an electric transmission station in Kiev, the capital of Ukraine. Each cyberattack lasted no more than six hours, but security experts were still alarmed: hackers had just demonstrated their ability to infiltrate the grid and drastically alter the flow of society.