All of the above. The USMC is designed to be quickly deployed in such a way that combat operations can continue to be performed with no support dependency (1-3

All of the above. The USMC is designed to be quickly deployed in such a way that combat operations can continue to be performed with no support dependency (1-3 months, I don't remember). In order to make that happen they've duplicated a slimmed down version of a bunch of DOD components: air, armor, artillery, navy, etc. The moment one of those components underperforms in comparison to the fatter DOD version - it calls the whole endeavor into question, so there is considerable incentive to the folks at the top to make it work. Long story short: the USMC is a statically compiled version of kill.exe. They rotate the pilots to ground operations as well, FACs - forward air controllers, so there is a pretty close link at the company level: the FAC knows the pilots in the air. Rifle squad leaders are required to be qualified JFOs, joint fire observers, so for every 13 infantrymen you've got someone who can direct fire support. The common practice in the infantry is for individuals to train in tasks performed by the next two levels in one's chain of command, so every rifleman is effectively trained to interface with fire support. This requirement for interoperability is often reflect in weapon design: tanks have comm boxes on the back, grunt phones, where an infantryman can grab the phone and direct the tank commander. This leads to the implementation of the "billet supersedes rank" philosophy, where you often have a lance corporal instructing an officer - and the instruction is cheerfully met with "Direct fire B2, fire for effect, aye aye lance corporal". The effect of the culture can't be overstated, I've seen a lot of brave men from every branch, but in my experience as an infantry machinegunner - the USMC air wing operated on a whole other level of "Just make it happen". Judgement calls are made at a much lower level in the Corps, which can lead to emotion driven mistakes, but generally results in faster decisions by those with greater situation awareness.