In early 2018, a Facebook user made a public threat on the social network against one of the company’s offices in Europe.

Facebook picked up the threat, pulled the user’s data and determined he was in the same country as the office he was targeting. The company informed the authorities about the threat and directed its security officers to be on the lookout for the user.

“He made a veiled threat that ‘Tomorrow everyone is going to pay’ or something to that effect,” a former Facebook security employee told CNBC.