In what would appear to be a sign that no social-media platform is truly safe from foreign interference, William Evanina, the head of U.S. counter-intelligence, told Reuters on Friday that Chinese intelligence services have been using LinkedIn to recruit Americans as spies. “I recently saw that Twitter is canceling, I don’t know, millions of fake accounts, and our request would be maybe LinkedIn could go ahead and be part of that,” Evanina told Reuters. China’s “super-aggressive” efforts reportedly include Chinese espionage services creating fake LinkedIn accounts, with the goal of recruiting Americans who have access to commercial and government secrets. According to Evanina, Chinese spies have contacted thousands of LinkedIn users at a time, targeting not only government workers, but specialists in academia and the corporate world, too.

It’s not clear how successful the practice has been. We know that in June, Kevin Mallory, a retired C.I.A. officer, was convicted on espionage charges after being recruited via LinkedIn to spy for China (he was arrested while returning from Shanghai with $16,000 in undeclared cash). If anyone else has been recruited, Evanina didn’t say. Still, such Chinese espionage attempts wouldn’t be unprecedented. German and British intelligence services claimed previously that the Chinese had targeted German government workers. “Chinese intelligence services are using new strategies of attack in the digital space. Social networks, especially LinkedIn, are being used in an ambitious manner to gather information and for recruitment. We are dealing with a broad attempt to infiltrate parliaments, ministries, and administrations,” Hans-Georg Maassen, the head of the Federal Office for the Protection of the Constitution, Germany’s domestic security agency, said in December.

LinkedIn, for its part, says it removes fake accounts and state-sponsored activity from its platform. “We actively seek out signs of state-sponsored activity on the platform and quickly take action against bad actors in order to protect our members,” LinkedIn spokesperson Nicole Leverich told Gizmodo. “We don’t wait on requests, our threat-intelligence team removes fake accounts using information we uncover and intelligence from a variety of sources including government agencies. We enforce our policies, which are very clear: the creation of a fake account or fraudulent activity is a violation of our terms of service.”

News of the Chinese campaign suggests that foreign intelligence campaigns in the U.S. are likely even more aggressive, and widespread, than is commonly understood. While the majority of media reports surrounding such intelligence operations has focused on Russian activity on Facebook, LinkedIn is a comparatively small and specialized platform, primarily used by job-searchers and recruiters, with about 575 million users worldwide. That LinkedIn, the stodgiest and most utilitarian social-media platform, has been targeted by spies is further confirmation of how dedicated foreign operatives are—and the extent to which they see opportunities to recruit.

LinkedIn “is a victim here,” Evanina told Reuters. “I think the cautionary tale . . . is, ‘You are going to be like Facebook. Do you want to be where Facebook was this past spring with congressional testimony, right?’” The comparison to Facebook, which is heading to Capitol Hill next week to answer questions from lawmakers about disinformation and has been dogged by scandal for months, is not a flattering one.