>>64143671
Ooh, ooh! I can answer this!
Prior to the M-16's adoption (autistic note: the USAF never participated in the XM-16 program and instead used Model 604s bought directly from Colt) the USAF used M1 carbines, believing that they were simpler to use and easier to train a new recruit on than a Garand or M-14, freeing up more time for technical training. By the 1960s the Air Force's WW2 aged carbines were starting to get old and worn out, and any replacement weapon would be considered primarily based on simplicity and ease of use. The fact that the AR-15 was adopted was due to a fortunate coincidence in that Air Force Chief of Staff Curtis LeMay was touring Armalite's parent company Fairchild and met Eugene Stoner, who showed him a demonstration of the weapon.
During the Vietnam War (and to a lesser extent, Korea and WW2) the concept of airbase security as a doctrine was developed. In Vietnam specifically, Project Safeside was an Air Force initiative that expanded strategic awareness for the airbase defense mission that expanded the role of USAF security not just to the airbase perimeter, but further out to any key terrain features that could be used by adversaries to stage attacks. Airmen were, in fact, climbing up mountains to capture ground in close combat.
One of the biggest failures in USAF doctrine was the overbearance of interior close-in aircraft security rather than perimeter security. The Security Police career field was split in half between two sections: Law Enforcement and Airbase Defense, and the two halves didn't talk to each other or work together. Standard Operating Procedure was to place a guard next to each aircraft individually to protect it from sabotage, but this came at the expense of not having enough troops to defend the perimeter of the base. During the battle of Tan Son Nhut during Tet, the sector of the base that got breached was manned by only five airmen.
