Translation guide
The military branch that conducts aerial warfare. In Japanese, the most common term is 空軍 (kuugun), but Japan's own air force is officially called 航空自衛隊 (koukuu jieitai) due to constitutional naming conventions.
Referring to the air force of any country in a general sense.
Standard word for 'air force'. Used for most countries' air forces.
The United States Air Force is one of the largest air forces in the world.
He wants to become an air force pilot.
Specifically referring to Japan's own air force, which is technically a self-defense force.
Referring to air forces that use a different term, such as 'air corps' or 'air arm'.
Used for some historical or smaller air forces, like the Imperial Japanese Navy Air Service or some current naval air arms.
The Imperial Japanese Navy's air corps participated in the attack on Pearl Harbor.
Due to Article 9 of the Japanese Constitution, Japan does not maintain a traditional military. Its air force is officially the 航空自衛隊 (Air Self-Defense Force). Using 空軍 for Japan's force can be politically sensitive or technically incorrect. For other countries, 空軍 is fine.
In Japanese media, you may see 空自 (kuuji) for Japan's ASDF, 米空軍 (beikuugun) for the US Air Force, and 英空軍 (eikuugun) for the Royal Air Force. These are common abbreviations.
There's an event where you can tour an ASDF base.