Facebook has announced that it will notify users that have been targeted by an attacker suspected of spying on them. The company’s chief security officer, Alex Stamos, explains that the warning is necessary because government-sponsored attacks are “more advanced and dangerous than others”. He declined to explain how Facebook can tell the difference from attacks from nation states as opposed to conventional spying so as to “protect the integrity of our methods and processes.”

Specifically, Stamos issued the following message: