The Air Force said Friday Secretary Michael Donley plans to step down as the service’s top civilian June 21 after serving in the position for nearly five years.

Donley was confirmed as the 22nd Air Force secretary on Oct. 8, 2008. In addition to serving as the acting secretary since June 2008, Donley also served as secretary for seven months in 1993, making him the longest serving Air Force top civilian, according to the service. He also served as the Air Force’s top financial officer from 1989 to 1993.

The Air Force said Donley has not announced any future plans.

“The Air Force has been a way of life for so much of my career, I know it will be bittersweet to say farewell,” Donley said in a statement.

Donley’s 35 years of experience in the national security committee also includes service in the Senate, White House and Pentagon. Prior to becoming Air Force secretary, Donley served as the director of administration and management in the Office of the Secretary of Defense (OSD).

“Mike has been an invaluable adviser during my first two months as secretary of defense and has been an outstanding leader of the Air Force for nearly five years,” Defense Secretary Chuck Hagel said Friday in a statement. “His leadership came during a challenging time for the Air Force and he helped instill a culture of responsibility, initiative, and professionalism to the service. Mike has been an unwavering champion for our airmen, their families, and for American airpower.”