He enlisted in September 1942 in the United States Army Air Forces and entered civilian pilot training and the aviation cadet program.
Westberg served from June 1944 to April 1945 with the Fifteenth Air Force in Italy and flew 35 combat missions in B-24 Liberator bombers.
He served from October 1954 to August 1957 at March Air Force Base, California, in staff and command positions, flying B-47 Stratojets with the 22d and 320th Bombardment Wings.
After graduation from the National War College in August 1967, General Westberg served at Shaw Air Force Base, South Carolina, as commander of the 363d Tactical Reconnaissance Wing, and was an RF-4C Phantom pilot.
His military decorations and awards include the Silver Star, Legion of Merit with oak leaf cluster, Distinguished Flying Cross with oak leaf cluster, Meritorious Service Medal, Air Medal with 16 oak leaf clusters, Air Force Commendation Medal, Presidential Unit Citation Emblem, Distinguished Unit Citation Emblem, and the Air Force Outstanding Unit Award Ribbon.