After graduation from the academy, he attended flying training school at Williams Air Force Base, Arizona, and was awarded pilot wings in 1951.

During the Korean War Leavitt served in South Korea as a pilot and flight commander with the 58th Fighter-Bomber Wing.

He later was chief of standardization in the 4028th Strategic Reconnaissance Weather Squadron at Laughlin Air Force Base, Texas.

Following graduation from the National War College in August 1967, Leavitt was assistant deputy commander for operations of the 36th Tactical Fighter Wing at Bitburg Air Base, Germany.

From April 1970, he was vice commander of the 8th Tactical Fighter Wing at Ubon Royal Thai Air Force Base, Thailand.

He was responsible for operational and intelligence matters affecting Air Force units in Europe and the Middle East.

[1] He has been criticized for his handling of the Damascus accident, including waiting several hours to develop a plan as the missile leaked fuel, overruling experts on the ground, issuing the order for a crew to activate an exhaust fan that likely caused the explosion, and placing blame for the disaster on lower-level personnel.