Not so true anymore
Military R&D as a share of GDP is much lower than it was in the 1960s, and similarly military R&D compared to total commercial sector R&D is much lower. The gap between the military labs and the private sector is just a lot less than it used to be.
The R&D is also more specialized. There was a lot of fundamental work in aeronautics and electronics back then, much of it DoD funded but university-based.
Now, the research is more likely to be done by major contractors and focussed on narrower defense applications, like anti-radar coatings or IED detection systems.