White House Chief of Staff John Kelly had one of his personal email accounts hacked by an unknown intruder, he told staff, according Buzzfeed. Kelly wrote "one of my own accounts has suffered recently" from a cyber intrusion and instructing staff to limit their use of email to thwart leaks and public attempts to obtain transparency through the Freedom of Information Act. The letter was obtained by Buzzfeed through FOIA.

The email affirms October 2017 reporting from Politico that White House officials believed Kelly’s personal phone had been hacked towards the end of 2016, shortly before the Trump administration took office. The National Security Agency reportedly told White House staff last year to avoid using personal email accounts and cell phones and assume that their accounts and devices had already been breached by hostile foreign intelligence services. Former White House Communications Director Hope Hicks told to the House Intelligence Committee that her email account had been hacked.

White House staffers in Trump administration are hardly alone in finding themselves in the crosshairs of foreign cyberspies. Russian hackers reportedly broke into President Obama’s own email account in April 2015 as part of a campaign of intrusions that saw breaches into the State Department and Joint Chiefs of Staff’s email networks.

White House officials have tried to institute a ban on personal cell phone use among staff, with conflicting reporting on whether the move has more to do with preventing leaks or improving cybersecurity. The ban, however, does not apply to Trump himself. As recently as last month, the president was reportedly continuing to use an unsecured commercial cell phone in order to tweet and browse Twitter—resisting the advice of White House officials who urge him to swap out the phones and allow them to be swept for signs of intrusion.

The Washington Post reported last week that Department of Homeland Security discovered “rogue” surveillance equipment located near the White House like International Mobile Subscriber Identity (IMSI) catchers and stingrays, devices designed to imitate legitimate cell towers and trick phones into providing sharing a user’s communications.