For a time this year, behind-the-scenes opposition from Hayden and questions about any responsibility Alexander might have borne for the Abu Ghraib prison scandal in Iraq threatened to block Alexander's advancement to NSA chief.
His role as the Army's deputy chief of staff for intelligence generated concerns on Capitol Hill about whether Alexander's position linked him to abuses at Abu Ghraib, which included allegations of misconduct by Army intelligence officers. But Alexander was able to convince senior members of Congress, in private discussions, that he had no direct responsibility for the activities in Iraq and no involvement in any interrogations.
Alexander said he had pushed for the initial Army investigation into Abu Ghraib and worked to incorporate those lessons into Army training plans.
Once members of Congress "understood that, it [Abu Ghraib] was not a big issue," Alexander said. He was confirmed as NSA director July 29, shortly before Congress left for its August recess.
Alexander is quick to play down reports of tension with Hayden, although he chooses his words carefully.
Noting that he received his job offer from National Intelligence Director John D. Negroponte in May, Alexander said, "General Hayden was very supportive from May on." Hayden serves as Negroponte's top deputy.
`The Odd Couple'
Alexander likened his and Hayden's relationship to The Odd Couple, about two housemates with incompatible lifestyles - though he did not say who's who. At a meeting with NSA employees this month, he addressed the issue head-on.
"Let's be real honest. I know you read in the paper that there's this big fight going on between, you know, Jack Lemmon and Walter Matthau. Well it's not true," Alexander said. "They do discuss."
He added: "Look at what General Hayden's done. ... Our country owes him a great debt of gratitude."
Alexander said he and Hayden agree on "99 percent" of what they talk about.
Talent for innovation
Colleagues praise Alexander's technical skill and nearly photographic memory. As a junior intelligence officer during the Gulf War, he regularly provided his commander with an understanding of the enemy forces, Noonan said.
"He was the poster child of someone who really knew the intelligence business," Noonan said.
A decade ago, when Alexander was told by superiors that an eavesdropping system he hoped to build was impossible, he responded by getting a group of aides together to assemble a proposal for a mobile unit to collect a specific satellite signal.
The NSA director finally agreed to provide $1 million for the project, and Alexander had it in the field within about a year. As head of Army intelligence, Alexander put special emphasis on getting battlefield troops the information they needed.
His talent for innovation is not limited to spycraft. He also makes his own golf clubs.
"I did that for some of our allies," including officials from Korea and Japan, he said.
Former colleagues said Alexander is not shy about piling work on subordinates but he does so with good humor and a hands-on approach.
"Keith always impressed me as the guy who wasn't afraid to get down into the trenches and talk to the troops," said Rich Haver, a former Defense Department intelligence official.
Town hall meeting
On his second day at the NSA, Alexander called a town hall meeting to introduce himself and take questions from some of the agency's 32,000 employees.
"You work for the secretary of defense," one employee said. "You work for Dr. Cambone. You work for General Hayden. You work for Ambassador Negroponte. You work for the vice president. You work for the president. So who's your real boss?"
Alexander, who sometimes lapses into self-deprecatory, if corny, humor, had a quick response: "My wife."
Though artfully evaded, the employee's question goes to the heart of what experts said Alexander must do to succeed - either work with or around those above and below him to accomplish the projects he sets out for the agency.
A transcript of The Sun's interview with the NSA's director, Lt. Gen. Keith B. Alexander, is available online at www.baltimoresun.com/alexander.
Keith B. Alexander
Personal: 53; born in Syracuse, N.Y., the middle of five children. His father, a World War II Marine, is a retired engineer, and his mother is a nurse. Married for 31 years to Deborah Douglass, whom he met in high school but did not date until later. Four daughters; four granddaughters. Speaks French and German.
Education: Westhill High School: ran track and cross country. U.S. Military Academy: bachelor's degree; member of sport parachute team. Boston University: master's degree in business administration. Naval Postgraduate School: master's degrees in electronic warfare and physics. National Defense University: master's degree in national security strategy.
Hobbies: Golf and early-morning workouts at the gym with his wife, a former teacher. "She doesn't want me to turn into a beach ball," he says.
Career highlights: Platoon leader and commander of military intelligence battalion, U.S. Army, Germany; assistant chief of staff for intelligence, Operation Desert Storm, Iraq; commanding general, U.S. Army Intelligence and Security Command, Fort Belvoir, Va.; director, National Security Agency, Fort Meade.