Dustin Volz reports the other intrusion may have exposed personal information of intelligence and military personnel who filled out Standard Form 86 questionnaires for national security positions.
U.S. authorities believe that both attacks originated from China.
The Obama administration on Friday launched a new cybersecurity initiative to bolster protection of federal computer systems, Julian Hattem reported for The Hill newspaper.
The 30-day program calls for strategies to fix system vulnerabilities, limit access to privileged data and implement multifactor authentication tools, the report noted.
Hattem said U.S. Chief Information Officer Tony Scott is working with officials at the National Security Council and the departments of Defense and Homeland Security to review cyber policies and practices across the government.