The White House's acting cyber-security tsar has resigned from her post, according to the Wall Street Journal.
Melissa Hathaway told the paper she was leaving for "personal reasons" and would return to the private sector.
The former strategist was appointed as acting national cyber-adviser in February and was expected to be offered the post of full time.
President Barack Obama has said that cyber-security is a high priority for his administration.
In May, the President announced plans for securing American computer networks against cyber attacks.
In recent years, US government and military bodies have reported attempts to infiltrate systems by hackers.