Gen. Keith Alexander, the director of the National Security Agency and the head of U.S. Cyber Command, will step down sometime in the spring, according to a Pentagon spokeswoman.
The official said Alexander's decision has "nothing to do" with the leaks by former government contractor Edward Snowden, which unveiled new details about federal surveillance programs and sparked a public backlash against the agency.
Alexander, who took the helm of the NSA in 2005, is the longest serving director in agency history.
A leading candidate to replace Alexander is Vice Adm. Michael Rogers, currently the commander of the U.S. Navy's 10th Fleet and U.S. Fleet Cyber Command, officials told Reuters.
The military spokeswoman noted that Alexander's tenure was already extended three times: in 2009, 2010 and 2013.
"The decision for his retirement was made prior; an agreement was made with the [secretary of defense] and the [chairman of the Joint Chiefs of Staff] for one more year, to March 2014," the spokeswoman said.
Laura Magnuson, a White House spokeswoman, confirmed that Alexander told President Obama several weeks ago that he plans to step down in spring 2014.
"General Alexander has served an extraordinary tenure and capably led these agencies through critical periods of growth and transition," Magnuson said. "The President looks forward to continuing to work with General Alexander until his term is complete and thanks him, and the men and women of the NSA, for their patriotism and dedication as they work every day to keep us safe."
In addition to being the head of the surveillance agency, Alexander also leads U.S. Cyber Command, a team of military hackers that trains for offensive cyberattacks and protects U.S. computer systems.
Critics argue that uniting the two roles centralizes too much power in the hands of one official. But Alexander has argued that it is important that NSA and U.S. Cyber Command work closely together.
Since the Snowden leaks put the NSA in the spotlight, Alexander has launched a public relations campaign to try to rally support for the controversial surveillance programs. In public speeches and in open and classified congressional hearings, Alexander has argued that the programs provide critical information to thwart terrorist attacks. He also claims officials are careful to protect privacy rights.
But several lawmakers, including Senate Judiciary Committee Chairman Patrick Leahy (D-Vt.), are working on legislation to rein in the NSA's power and toughen oversight.
—Updated with White House comment on Oct. 17 at 11:04 a.m.