From spy planes to cyberattacks to the private lives of foreign leaders, the president gets access to more confidential material than anyone else on the planet. Now, it's all in Donald Trump's hands. When Dwight Eisenhower was elected president in 1952, outgoing president Harry Truman informed him of an important secret: Days before the election the United States had tested the world's first hydrogen bomb in the Pacific. The nation now possessed a weapon roughly a hundred times as powerful as any before—and almost nobody else knew. Eight years later, when Eisenhower handed the keys to John F. Kennedy, his administration passed along its own secret: America had a covert plan underway to invade Cuba. Kennedy let the Bay of Pigs mission proceed, and the result was a fiasco that would take the world to the brink of nuclear war. The president of the United States has more access to official secrets than any other human being in the country—and the potential to know more about the world than