n June 14, 2016, the Washington Post reported that Russian hackers had broken into the Democratic National Committee’s files and gained access to its research on Donald Trump. A political world already numbed by Trump’s astonishing rise barely took notice. News reports quoted experts who suggested the Russians merely wanted more information about Trump to inform their foreign-policy dealings. By that point, Russia was already broadcasting its strong preference for Trump through the media. Yet when news of the hacking broke, nobody raised the faintest suspicions that Russia wished to alter the outcome of the election, let alone that Trump...