The breach has already rattled the bureau, but now threatens to turn into a serious counterintelligence risk, said Eric O'Neill, a former FBI operative who founded the cybersecurity consultancy Nexasure AI.

O'Neill said the presence of ​medical data was a sign that the hack was approaching the same kind of magnitude as the 2015 intrusion into the Office of Personnel Management, which ​exposed millions of Americans' sensitive clearance information, allegedly to Chinese intelligence.
He added that the data would be a powerful magnet for ⁠hostile spies.

"I would be shocked if Russian intelligence isn't knocking on their door and saying, 'We want that stuff, hand it over,'" said O'Neill.