The Air Force must balance its legacy of combat fighters with the surveillance, space, transport and cyber missions that will dominate future wars, Defense Secretary Robert Gates said Friday.

He told cadets at the U.S. Air Force Academy that there still a pressing need for American air supremacy as countries such as China and Iran pursue longer range weapons and air defense missiles.

Developing more sophisticated fighter jets is critical, the Pentagon chief said. But he also said air-to-air combat and bombing must not continue to dominate the Air Force culture to the neglect of other capabilities needed to fight terrorists and hostile nations are neglected.

Gates, who 44 years ago was commissioned as an Air Force second lieutenant, has had an often tumultuous relationship with that military branch during his four-year tenure at defense secretary. He touched on those sore points in his speech, even as he praised the airmen for their lifesaving roles in the Iraq and Afghanistan wars.

He cited their rapid transporting of wounded troops and the delivery of equipment and supplies. The service has provided Gates one of his more critical war-fighting tools — drones. The insatiable demand for unmanned aircraft has created a new crop of pilots who remotely operate drones over Afghanistan and Iraq from their work stations thousands of miles away.

Pushing the fighter-entrenched Air Force to move quickly to send drones to war, he said, was like "pulling teeth."

As a potential legal challenge dissolved Friday to the Air Force's decision to award a $35 billion tanker contract to Boeing Co., Gates warned that pricey refuelers will contribute to tough funding problems ahead.

"The Air Force is going to face a big challenge," Gates told cadets at the Air Force Academy in Colorado Springs, Colo. "Whether we can fund a new tanker, F-35s, a new bomber and all of these other capabilities simultaneously, I think, is going to be a tough question that people will have to confront."

For the near term, however, he said the military has cut or curtailed as much as $330 billion in future spending projects, so at this point he does not see any other major defense programs on the cutting block for the next year or two.

Gates' has had a tense relationship with the Air Force brass, especially over a series of embarrassing nuclear lapses and contracting debacles.

The nuclear stumbles raised Gates' ire during his first year on the job. In August 2007, six nuclear-armed cruise missiles at Minot Air Force Base, N.D., were mistakenly loaded onto a B-52 bomber and flown to Barksdale Air Force Base, La., without the bomber crew knowing they were aboard.

Less than a year later, the U.S. mistakenly shipped to Taiwan four electrical fuses designed for use on nuclear intercontinental ballistic missile. Soon after, an angry Gates sacked Air Force Chief of Staff Gen. Michael Moseley and Air Force Secretary Michael Wynne for failing to fully address the foul-ups.

Independent reviews condemned the Air Force for a dramatic deterioration in managing the U.S. nuclear arsenal. Since then, the service has instituted broad changes to improve oversight and management of the nuclear mission and inventory.

Gates also struggled with the service over its error-prone contracting process for the much-needed airborne refueling tanker.

The $35 billion tanker deal to build 179 tankers was awarded last week to Boeing Co. after nearly a decade of bungling.

Air Force plans to lease Boeing planes fell through, and the first contract award — to the European Aeronautic Defence and Space Co. — was thrown out due to significant errors.