Chinese spies are increasingly recruiting U.S. intelligence officers as part of a widening, sustained campaign to shake loose government secrets.

Senior U.S. law enforcement and intelligence officials have escalated their warnings characterizing Chinese espionage as the single most significant long-term strategic threat, encompassing both spycraft intended to steal government secrets and the sustained heist of intellectual property and research from the corporate and academic worlds.

While the Trump administration has sought to emphasize the damage of Beijing’s economic espionage—an area of focus in bilateral trade talks—current and former U.S. officials say China has also grown bolder and more successful in traditional spy games, including targeting less conventional recruits.

The effort is being abetted by an ocean of hacked personal data that may help pinpoint who is vulnerable to inducements.

A series of recent espionage cases, including that of a former Central Intelligence Agency case officer who was scheduled to go to trial next week, show the breadth of Chinese efforts to use U.S. intelligence personnel to gain access to nonpublic information from the government.