AP Style holds that “air force” should be capitalized when it is referring to U.S. Forces. For example,
- The U.S. Air Force is a branch of the military.
- The Air Force has requirements for entry.
- Air Force rules and regulations are strict.
Do not use the abbreviation USAF.
In 1941, the U.S. Congress established the Army Air Forces (note the “s”). Prior to this, the air arm was known as the U.S. Army Air Corps. The U.S. Air Force (no “s”) was created as a separate service in 1947.
AP Style holds that you should use lowercase for the forces of other nations. For example,
- The Israeli air force gave aid to the U.S. troops.
This approach has been adopted for consistency because many foreign nations do not use “air force” as the proper name of their specific branches of military.