In theory at least it is the "combat developments" community that writes the requirements for future military systems and products. Those elements are part of the branch schoolhouses -- U.S. Army Infantry School, Armor School, etc. The combat developers write the system requirements documents which then have to be staffed and approved by a half-dozen echelons within the TRADOC/DA bureaucracy.

It is the "materiel developers" who cut metal and develop prototypes. Those organizations belong to Army Materiel Command, except for those of the Medics and parts of the crypto Signal community.

Even after the Soviets collapsed we continued developing weapons for Fulda Gap threats until the "Transformation" net-centric initiative started. The rest is fairly recent history.