Air Force Gen. Victor E. Renuart Jr. has four stars on his collars and 60 combat missions under his belt. But on a recent trip to a California airfield, he sprang from an SUV like a happy kid and charged toward a crowd of servicemen and women.

"Hi, guys!" he said to the troops, who stood stiffly at attention. "Relax, relax, relax!"

Renuart, commander of the U.S. Northern Command, seems unnaturally upbeat and energetic for a man whose job is to figure out what disasters might befall the American homeland, and then lay plans to prevent or cope with them.

His conversation is peppered with references to hurricanes, pandemics and nuclear explosions, and he admits his responsibilities can be sobering. But he loves his job.

"I think we're doing really good things for the country, so that makes it easy to come to work every day," he said.

In a wide-ranging interview with The Associated Press aboard a small passenger jet, Renuart spoke about the Northern Command's growing pains and its efforts to put other agencies at ease about its intentions. He insisted the command is ready to take on what threats may come and is becoming better prepared all the time.

Renuart (REN-yoo-art) joined the Air Force in 1971 and commanded a fighter squadron during the first Gulf War. He oversaw all combat operations in the Iraq and Afghanistan wars when he was director of operations for the U.S. Central Command from 2001 to 2003.

He later served as senior military assistant to then-Defense Secretary Donald Rumsfeld and his successor, Robert Gates.

Renuart took the reins of both the Northern Command and the North American Aerospace Defense Command, or NORAD, in March 2007. NORAD monitors air and space threats against the U.S. and Canada, while the Northern Command oversees the military's homeland defense and supports civilian authorities. Both are headquartered at Peterson Air Force Base in Colorado Springs.

NORAD turned 50 this year, but the Northern Command _ created in 2002 in response to the Sept. 11 terrorist strikes _ is not yet 6 years old, and Renuart is only its third commander. Still, he tells his staff, "We're an adult now. We're not growing anymore."

He said the command had to learn to get things done by persuasion and coalition-building because it has very few troops and little equipment under its direct control.

"In many ways our ability to lead is in how we create consensus, build focus and move the command and our teammates toward a common result," he said.

"I think our command is unique in that regard. ... All (military commands) have a consensus-building process, but we are truly almost totally dependent on that."

When Northern Command was created, some civilian and military leaders worried it would try to grab at least partial control of the National Guard. It has taken some work to get past that, Renuart said.

"It was getting the institutions to create a level of trust among one another, that Northcom wasn't making a run on National Guard forces to be somehow in command of them. Northcom was trying to be the integrator, so that we had the best integrated team to conduct the operations," he said.

Northern Command will gain more flexibility on Oct. 1 when a specialized military unit designed to respond quickly to a catastrophe comes on line. It will have 4,000 troops in three groups: first responders, a second wave of medical and logistics forces and a final wave of aircraft units, engineers and other support forces.

Two similar units are scheduled to start up over the next two years.

Renuart said Northern Command planners are working through a set of 15 disaster scenarios, including earthquakes, disease, fires, attacks and explosions, ranking them by "most dangerous" and "most likely" and then mapping out detailed response plans.

A nuclear explosion would be the most dangerous single event, he said.

"But frankly, a pandemic influenza may be the most dangerous in terms of the speed at which it could move across the country and the numbers of people affected," he said.

A more likely disaster would be a big, non-terrorist-related chemical plant explosion, Renuart said.

"We have industrial accidents in our country on some regular basis. As much as you continue to work to make our industry safer, that happens _ human error or material error or whatever," he said.

Although some reports have questioned how well prepared the U.S. is for another catastrophic attack or natural disaster, Renuart says his command is ready.

"I'm absolutely confident," he said, citing a new readiness reporting system in his command that allows him to see if any unit falls below personnel and equipment benchmarks.

Asked whether the Iraq and Afghanistan wars and homeland defense needs have stretched the military too thin, Renuart acknowledged active-duty troops are "still very busy" and retention rates at some ranks are below what the Pentagon would like.

But he said the drawdown of Iraq troops will help. Recruiting trends are improving, he said, and Defense Secretary Gates is committed to more predictable rotations with more time at home.

"Ideally we will get to the point over the next few years where you can expect to be gone for a year and home for two," he said.