At this point, nothing more needs to be said to describe Elon Musk’s seeming personality shift over the past two decades—but particularly over the past five years. Why that’s happened is a more interesting topic, and one that Ronan Farrow delves into deeply in this well-sourced, well-reported exploration of the entrepreneur’s increasingly influential role on the global geopolitical stage.

National-security officials I spoke with had a range of views on the government’s balance of power with Musk. He maintains good relationships with some of them, including General Mark Milley, the chairman of the Joint Chiefs of Staff. Since the two men met, several years ago, when Milley was the chief of staff of the Army, they have discussed “technology applications to warfare—artificial intelligence, electric vehicles, and autonomous machines,” Milley told me. “He has insight that helped shape my thoughts on the fundamental change in the character of war and the modernization of the U.S. military.” During the Starlink controversy, Musk called him for advice. But other officials expressed profound misgivings. “Living in the world we live in, in which Elon runs this company and it is a private business under his control, we are living off his good graces,” a Pentagon official told me. “That sucks.”