Records that included sensitive information about 21.5 million Americans have been stolen by hackers from the U.S. Office of Personnel Management (OPM). The records included Social Security  numbers of people who have undergone background checks for security clearances (and in some cases, their spouses) since 2000.

Investigators believe the the hack is related to an incident last month when information on about 4.2 million current and former federal workers were stolen. China has been identified as the leading suspect.

Cover image: Wikimedia