A relatively small number of Twitter users have been informed that their accounts have been targeted by state-sponsored hackers. Notifications began appearing in the inboxes of affected users two days ago. Twitter said in the notification that the hackers are possibly associated with a government, and were trying to steal users email addresses, IP addresses and phone numbers attached to accounts. It s unclear whether Twitter was compromised, or whether the accounts were targeted individually. Facebook announced in October that it would begin warning users of nation-state attacks because of their sophistication.
Source: https://threatpost.com/twitter-warns-some-users-of-nation-state-attacks/115633/