LACKLAND AIR FORCE BASE, Texas — For a service usually stationed so far from the front lines that it has earned the sobriquet Chair Force, some of the scenes now unfolding at the Air Force's primary training base almost seem blasphemous.

New recruits are being issued rifles. They are being taught hand-to-hand combat skills. They are being trained as battlefield medics. It's part of a complete revamp of basic training ordered by Air Force commanders in somewhat belated recognition that their airmen, once sent to large, isolated bases with thousands of infantrymen between them and enemy forces, are now regularly in harm's way.

Already in Iraq, the Air Force has taken over supply convoys to ease the burden on the Army and Marine Corps, and specialized forces have been used in Army-like combat patrols, conducting raids and seizing suspected insurgents outside facilities such as Balad Air Base, north of Baghdad.

It is hard to underestimate how radical a cultural change the move is for the youngest of the armed services.

The shift dovetails with the larger military needs of the wars in Iraq and Afghanistan and the hunt for terrorists. But it is a delicate balancing act, as the Air Force attempts to adapt to a world of guerrilla warfare even as it insists it is remaining true to the reason it was created — wielding dominant air power.

The Air Force views itself as the "high-tech service," responsible not only for sophisticated fighters and bombers, but for most military space programs and the bulk of the U.S. nuclear deterrent. As a result, its recruits tend to have more education — last year 28.3 percent of enlistees had some college education, compared with 24.2 percent for the Army — and are as likely to join to become computer experts as armed warriors.

"In Air Force basic training we did not talk about the role of a warrior, we did not talk about weapons," said Col. Gina Grosso, a Harvard-educated personnel specialist in charge of revamping Lackland's curriculum.

In November, that all began to change.

As part of a revamped course ordered by Gen. T. Michael "Buzz" Moseley, the former head of air operations in Iraq and Afghanistan who took over as Air Force chief of staff in September, recruits now learn "warrior skills" from their first week at Lackland. About half of the program is dedicated to combat-related drills, such as defending an air base under attack or operating during a night mission.

Some Air Force officials acknowledge that part of the training overhaul — and of the new land combat duties — is an effort to remain relevant in an age where opposing air forces are few and far between. Already, the Air Force is finding itself picking up missions that have historically been the sole purview of the Army or Marines.

Balad, for example, has long been one of the most dangerous areas for U.S. troops in Iraq, and the air base there has been attacked so frequently it became known as "Mortar-itaville." When Air Force Col. John Decknick first arrived there in the autumn of 2004, the Army units protecting the base from the rising insurgency were strained.

"They were working their butts off," Decknick remembers. "They were short-handed."

His bosses in the Air Force made the Army an offer: Since Balad was an air base, shouldn't the Air Force help protect it? The Army jumped at the offer, and three months later, a task force of 220 airmen was patrolling local villages and marshland, conducting nightly raids.

The mission lasted just 60 days and Decknick, who has spent 10 years helping expand Air Force ground security skills, said it remains a "test of concept." But it could be a sign of things to come.