When President Bush chose Richard Myers to be the new chairman of the Joint Chiefs of Staff, he saw the Air Force general as the man to help America meet "the changing threats of tomorrow."

No one knew tomorrow would come so soon.

Myers, now vice chairman of the Joint Chiefs, moves up to the top job on Monday facing a dramatically altered set of challenges from those envisioned when his nomination was announced on Aug. 24.

Although chosen to be the president's chief military adviser in large part because of his expertise in space-based defense, Myers still is an apt choice now that an all-out campaign against terrorism is the government's priority, say military analysts.

Many point to his fighter-pilot background as evidence he has the flexibility and creativity to grapple with an unconventional enemy.

"You don't last long in the fighter-pilot business if all you do is connect the dots," said retired Gen. Merrill McPeak, the Air Force chief in the early 1990s, when Myers was on his senior staff. "Myers' preparation from Day One has been to use his imagination, and that's what's required here."

"The stereotype of the military mind -- by the book, read it out of the regulations -- that's precisely what's not needed now."

Myers, 59, has a wide-ranging background that includes years as head of the U.S. Space Command, commander of U.S. forces in Japan, commander of U.S. forces in the Pacific, and vice chairman of the Joint Chiefs since the spring of 2000, a job in which he has helped conduct a sweeping reassessment of the armed forces. He has logged more than 4,000 flying hours, including 600 in combat in Vietnam.

"He's not coming out of an Air Force stovepipe," said William Taylor, a senior adviser at the Center for Strategic and International Studies. "He has a good, broad understanding of the role of the military to meet a number of threats worldwide."

Myers' tenure as vice chairman of the Joint Chiefs should help ensure a smooth transition from the current chairman, Army Gen. Hugh Shelton, who is retiring. As chairman, Myers will be the nation's top military officer, charged by Bush with helping bring about a transformation of the armed forces that balances conventional defense responsibilities with the ability to meet future threats.

Some find it an odd turn of events that the first chairman with a special operations background, Shelton, is being replaced with the first chairman with a space background precisely when the nation is heading into a conflict in which the clandestine warriors of "special ops" are expected to play a key role.

"Presumably, Myers is going to require a little Special Operations 101," said John Pike, director of GlobalSecurity.org, a think tank in Alexandria, Va. "Is he up to the job? We will let history judge."

Shelton said Thursday he felt like a quarterback taken from the game with his team one touchdown behind and ready to score. But he voiced confidence in Myers, saying, "I see an all-American quarterback suiting up."

McPeak says it would be a mistake to cast either Shelton or Myers as narrowly specialized.

"Myers is not a space weenie," McPeak said, pointing to his varied background. "What you need is mental flexibility and I don't see how we could have come up with a better candidate."

Myers' natural fit in Washington was evident when the terrorists struck on Sept. 11. He rushed from a meeting on Capitol Hill to the National Military Command Center inside the Pentagon even as most of the building was being evacuated.

"The air got a little acrid at times," he told his Senate confirmation hearing two days later. "The air filtration system shut down for moments. But we got it back up and were able to stay there throughout."

Looking to the job ahead, Myers already knows what will cost him sleep.

"What will keep me up at night in this job is those things that we haven't thought about," he told the senators. "There are probably more surprises out there. And my job and the job of the armed forces and everybody that supports us is to try to be as creative in our thinking as we can, to try to plug these seams and these gaps."

Even before the terrorist attacks, Myers had set the job of defining the military's role in "homeland defense" as one of his priorities.

"We've been tiptoeing around that issue for quite some time," he told senators. "My view is that this tragedy is going to help crystallize our thoughts."

Known for his easy manner and respectful treatment of service members in all branches of the armed forces, Myers is unlikely to match the rhetorical flourish of Colin Powell, the telegenic chairman of the Joint Chiefs during the Gulf War and now the secretary of state.

"Myers is the kind of guy who will give his advice in confidence," said McPeak. "He will be publicly on display and visible only when it's needed."