Starting Tuesday, look out for an unusual warning atop your Gmail inbox, Google home page or Chrome browser. It will not mince words: “Warning: We believe state-sponsored attackers may be attempting to compromise your account or computer.”

Google said it planned to issue the warning anytime it picks up malicious–possibly state-sponsored–activity on a user’s account or computer. How does Google know whether an attack is state-sponsored? It won’t say.

“We can’t go into the details without giving away information that would be helpful to these bad actors, but our detailed analysis—as well as victim reports—strongly suggest the involvement of states or groups that are state-sponsored,” Eric Grosse, Google’s vice president of security engineering, wrote in a blog post.

The announcement is timed just one week after security researchers discovered Flame, a massive, data-mining virus, had been spying on computers in the Middle East— predominantly in Iran– for at least the last four years.

Researchers say they believe the Flame virus is sponsored by the same entity that commissioned Stuxnet, a virus co-sponsored by the United States and Israel, that destroyed thousands of Iranian centrifuges in 2010.