Social media giant Facebook has begun warning users it suspects may have been subject to a state-sponsored attack.
Over the weekend, the company revealed it would start prompting users to turn on the 'login approvals' security mechanism if Facebook thinks the user's profile has been targeted or compromised by an attacker working on behalf of a nation state.
The notification will urge users to only allow access to their account through two-factor authentication. The 'login approval' feature alerts a user when their account is accessed from a new device or web browser, sending a code to the user's phone to enter in order to log in.
"We decided to show this additional warning if we have a strong suspicion that an attack could be government-sponsored," Facebook security chief Alex Stamos wrote in a notice.
"We do this because these types of attacks tend to be more advanced and dangerous than others, and we strongly encourage affected people to take the actions necessary to secure all of their online accounts."
Stamos stressed the warning was not related to a compromise of Facebook's infrastructure, and was intended to encourage consumers to rebuild or replace their affected computer or mobile device.
He did not disclose how the social media giant was able to pinpoint the infiltrations of end-user systems, arguing Facebook needed to "protect the integrity" of its methods.
Stamos did say the warnings to consumers would only pop up in cases where "the evidence strongly supports our conclusion".
Google has had a similar system in place since 2012.
Earlier this month, a European Union court struck down the 15-year Safe Harbour agreement between the US and EU that allowed for easy transfer of personal data between the two.
The decision was made partly as a result of NSA spying revelations by former contractor Edward Snowden.