Google has always put a lot of work into making Gmail secure. Their latest feature is interesting.
If Google’s system detects unusual attempts to access an account, they now show a warning on the top of the Gmail screen. They’re calling it a state sponsored attack. It doesn’t mean your account has been hacked, only that it’s the target of an attack.
If you ever see this, you’ll be advised to change your password (make it a strong password), and to enable two step verification – this will use your mobile phone as an additional way of protecting your account.