"The U.S. Office of Personnel Management (OPM) recently became aware of a cybersecurity incident affecting its systems and data that may have exposed the personal information of current and former Federal employees. DoD has been informed by OPM that some employee data has potentially been compromised in this incident and this note provides you with more information. Since the incident was identified, OPM has partnered with the Department of Homeland Security's U.S. Computer Emergency Readiness Team (US-CERT) and the Federal Bureau of Investigation to determine the impact to Federal personnel. As a result of this investigation, OPM is notifying approximately 4 million individuals whose Personally Identifiable Information may have been compromised. The notifications will be sent beginning June 8 and continuing through June 19 by email and U.S. mail."
Department of Defense: http://www.defense.gov/