US cyber security chief Randy Vickers has resigned after a string of cyber attacks on the websites of various US government agencies
Vickers, the director of the US computer emergency readiness team (CERT), stepped down on Friday and will be replaced temporarily by deputy director Lee Rock, according to Reuters.
No official reason has been given for the resignation, but it comes after a number of attacks on government websites, including the US Senate, the CIA, the FBI and other agencies.
The US CERT is responsible for the protection of US government computer networks, including those of the Pentagon and Senate.
Some pundits say the string of cyber attacks may not be the only reason for Vickers's resignation, which follows a number of high-profile resignations of Department of Homeland Security (DHS) cyber executives.
Vickers is the second high-profile DHS official to resign in recent months.
Philip Reitinger, deputy undersecretary for the National Protection and Programs Directorate at DHS, resigned in May
There have been six different directors of the centre in the past seven years.
A former director, Mischel Kwon, supposedly resigned in 2009 because of "obstacles and a lack of authority to fulfill [the] mission," according to the Washington Post.
Earlier that year, another DHS cyber security official, Rod Beckstrom, resigned, citing a lack of support inside the agency and what he described as a power grab by the National Security Agency.