By David Alexander and Mark Hosenball
WASHINGTON (Reuters) - President Barack Obama nominated on Thursday the U.S. Navy's top cyber warrior to head the National Security Agency, a move seen as a vote of confidence in a unit that is under fire for spying on Americans and their allies.
Navy Vice Admiral Michael Rogers, a cryptologist and head of U.S. Fleet Cyber Command, is not expected to immediately make major changes to the NSA, shaken by revelations by former contractor Edward Snowden.
"This is a critical time for the NSA, and Vice Admiral Rogers would bring extraordinary and unique qualifications to this position as the agency continues its vital mission and implements President Obama's reforms," Defense Secretary Chuck Hagel said in a statement.
"I am also confident that Admiral Rogers has the wisdom to help balance the demands of security, privacy and liberty in our digital age," Hagel said.
The NSA is under fire for monitoring the communications of Americans and allies abroad as well as those of potential U.S. enemies through a sweeping eavesdropping program, the scope of which was disclosed to the media by Snowden.
The documents that Snowden stole and leaked to the news media exposed the reach of U.S. surveillance activities, including the bulk collection of telephone records of millions of Americans, as part of counterterrorism efforts.
If confirmed by the Senate, Rogers would take over as head of both the NSA and the military's Cyber Command from Army General Keith Alexander, who is likely to retire in March or April. Rogers is a 30-year Navy veteran well versed in electronic surveillance.
"Obama is reaffirming his fundamental support for NSA and its surveillance projects despite the Snowden affair," said Bruce Riedel, a former CIA analyst who has sometimes advised the Obama administration.
In response to criticism over the NSA's surveillance practices, Obama vowed earlier this month as part of a series of reforms to ban eavesdropping on the leaders of allied countries and to begin reining in the collection of vast amounts of Americans' phone data.
Retired Gen. Michael Hayden, former director of both the NSA and the Central Intelligence Agency, said the nomination of Rogers was a vote of confidence in the signals intelligence community.
"This is a very solid team and one whose selection will calm anxieties at NSA over fears of new, misguided policies in the wake of the Snowden revelations," he said.
Hagel also said Rick Ledgett had been appointed as deputy director and senior civilian leader of the NSA. He replaces Chris Inglis, who retired this month.
Rogers will also lead Cyber Command, the military force responsible for defending the United States against cyber attacks. Obama had initially considered splitting the leadership of the two organizations, but decided against it.
(Reporting by Missy Ryan in Warsaw and David Alexander in Washington; Editing by Alistair Bell and Ken Wills)