This series, based on interviews with over three dozen current and former U.S. intelligence and national security officials, tells the story of China’s assault on U.S. personal data over the last decade — and its consequences. But instead, CIA officials believed the answer was likely data-driven — and related to a Chinese cyberespionage campaign devoted to stealing vast troves of sensitive personal private information, like travel and health data, as well as U.S. government personnel records. U.S. officials believed Chinese intelligence operatives had likely combed through and synthesized information from these massive, stolen caches to identify the undercover U.S. intelligence officials. It was very likely a “suave and professional utilization” of these datasets, said the same former intelligence official. This “was not random or generic,” this source said. “It’s a big-data problem.” The battle over data — who controls it, who secures it, who can steal it, and how it can be used for economic and security objectives — is defining the global conflict between Washington and Beijing. Data has already critically shaped the course of Chinese politics, and it is altering the course of U.S. foreign policy and intelligence gathering around the globe. Just as China has sought to wield data as a sword and shield against the United States, America’s spy agencies have tried to penetrate Chinese data streams and to use their own big-data capabilities to try to pinpoint exactly what China knows about U.S. personnel and operations.