LANGLEY AIR FORCE BASE, Va. - Defense Secretary Robert Gates launched the Air Force in a new direction yesterday by announcing an unusual choice as the service's next uniformed chief and by declaring an immediate halt to personnel reductions that he said had put the Air Force under too much wartime strain.

Before flying here to explain his moves to airmen and their commanders, Gates recommended that President Bush nominate Gen. Norton Schwartz, a 35-year veteran with a background in Air Force special operations, as Air Force chief of staff, replacing Gen. Michael Moseley, who has been sacked.

In a sweeping shake-up, Gates also formally sent former Air Force official Michael Donley's name to the White House to be the next secretary of the beleaguered service, to succeed Michael W. Wynne. Bush quickly announced he would nominate Donley, and designated him as acting secretary until he is confirmed by the Senate.

Gates announced on Thursday that he was removing Moseley from the chief's job and Wynne as its top civilian to hold them accountable for failing to fully correct an erosion of nuclear-related performance standards, a concern linked to the cross-country flight last August of a B-52 carrying armed nuclear weapons.

Gates said he felt compelled to sweep out the current Air Force leadership to halt a long-term drift in the service's focus. But he also made a point of praising the Air Force's contributions to the wars in Iraq and Afghanistan.

"Your contributions have made a lifesaving difference to those fighting on the ground," Gates said.

He noted that the Air Force has been engaged in combat continuously for 17 years, beginning with the 1991 Gulf War and including years of flying combat missions in "no fly" zones over northern and southern Iraq.

"Your families have also borne this burden, and the Air Force has its own fallen heroes - often struck down while serving on the ground alongside our soldiers and Marines," Gates said. "We know this, and we are working to ease the burden. For example, I intend immediately to stop further reductions in Air Force personnel."

In 2006 the Air Force began a multiyear reduction in its ranks, taking it from nearly 360,000 to an intended target of 316,000 by 2010. By halting further cuts, Gates would leave the Air Force with about 330,000 personnel, Air Force officials here said.

Schwartz had been thought to be in line for retirement, and his replacement as head of the U.S. Transportation Command, Lt. Gen. William Fraser III, had been announced in April.

But yesterday Gates recommended that Fraser be nominated as the next vice chief of the Air Force.

And he said Gen. Duncan McNabb, the current vice chief, should move to the Transportation Command job, succeeding Schwartz.

Donley served as acting secretary of the Air Force for seven months in 1993 and was the service's top financial officer from 1989 to 1993.

He is the Pentagon's director of administration and management, and has held a variety of strategy and policy positions in government.

Schwartz has held several high-level assignments on the Joint Chiefs of Staff, and has been commander of the U.S. Transportation Command since September 2005.

Schwartz, a pilot with more than 4,200 flying hours, served as Commander of the Special Operations Command-Pacific, as well as Alaskan Command, Alaskan North American Aerospace Defense Command Region, and the 11th Air Force.

He attended the Air Force Academy and the National War College, and he participated as a crew member in the 1975 airlift evacuation of Saigon.

In 1991, he served as chief of staff of the Joint Special Operations Task Force for Northern Iraq in operations Desert Shield and Desert Storm. *