President Clinton on Wednesday announced Michael P.C. Carns, a retired four-star Air Force general, as his choice to head the CIA, which has been without a permanent director since R. James Woolsey abruptly resigned in December.

"General Carns will face a challenge; its difficulty is matched only by its importance," Clinton said in announcing his selection in the Roosevelt Room of the White House. Present were leaders of the House and Senate intelligence committees.Carns, 57, spent 35 years in the Air Force. He retired last September after serving as vice chief of staff of the Air Force, its No. 2 official.

"He's a proven innovator, open to new ways of doing business and skeptical of conventional wisdom," Clinton said, noting that Carns had gained a reputation in the Air Force as a combat veteran and strong manager.

Carns said the job offer was unexpected.

"There is something about the opportunity to serve and the chance to make a difference that is simply irresistible," Carns said after being introduced by Clinton.

Clinton also thanked Woolsey for his nearly two years as CIA director. Woolsey, who was present at the announcement, said he left the post for personal reasons, but he had labored under a strained relationship with Congress.

Carns said CIA officers are "world-class professionals." He said it was time to make the spy agency more open, leaner and more willing to change its ways.

He said he intended to work closely with the congressional oversight committees and with a new presidential commission, headed by former defense secretary Les Aspin, that has begun studying ways of overhauling the intelligence agencies.

"I'll be proud to join your national security team," Carns told Clinton.

Carns declined to respond to questions from reporters. Clinton, however, spoke up for the CIA and said "they deserve credit for solving problems," including internal security problems highlighted by the arrest last February of Aldrich Ames, the CIA veteran who was convicted of selling secrets to Moscow.

In his prepared remarks, Carns said he realizes the CIA faces many tough challenges.

"The Cold War may have passed into history, but regional instability, terrorism, drug trafficking, crime and the proliferation of nuclear weapons all loom large," Carns said.

Carns, if confirmed by the Senate, would be the first military officer to head the CIA since Adm. Stansfield Turner in the Carter administration.

People who worked with Carns during his 35-year Air Force career said Tuesday they believed he would do well.

Carns, a native of Junction City, Kan., flew 200 combat missions in the Vietnam War. He was vice chief of staff of the Air Force when he retired last year.