updated 10:40 pm EDT, Tue June 5, 2012
Move comes in response to repeated foreign government attacks
Google is deploying a new alert system for users who may be victims of state-sponsored attacks on their accounts. The warning does not mean that the account has been hijacked, but is an indication that internal Google systems have flagged the account as a target of coordinated attacks from foreign states or state-sponsored groups. Google has declined to detail what intelligence leads to an account being flagged for an attack by governmental entities.
If a user receives the message, the official Google security blog recommends that users should immediately change their passwords so it has a mix of capital and lowercase letters as well as punctuation marks and numbers and is not a dictionary word. In addition, two-step verification should be enabled, and all OS patches should be applied.
Google has publicly addressed foreign attacks on its systems in the past. Google accused the Chinese government of hacking Gmail to suppress political dissent in March 2011. Other reports from Google targeted Chinese hackers assaulting US governmental official's Gmail accounts.