NSA used to do a lot of operating systems work, but no longer seems to do that.
[1] https://www.nsa.gov/Research/NSA-Mission-Oriented-Research/L...
.. a flexible MAC architecture was created and matured through a series of research systems. The work to bring this architecture to mainstream systems [and] experience with applying this architecture to mobile platforms is examined. The role of MAC in a larger system architecture is reviewed in the context of a secure virtualization system. The state of MAC in mainstream systems is compared before and after our work.
We describe our work to demonstrate an enhanced SMI transfer monitor (STM) to provide protected execution services on the x86 platform. An STM is a hypervisor that executes in x86 system management mode (SMM) and functions as a peer to the hypervisor or operating system. The STM constrains the SMI handler, by hosting the handler in a virtual machine (VM). Otherwise, the SMI handler holds unconstrained access to the platform, which could undermine the assurance provided by DRTM or TXT.
Implementation of SMI transfer monitor (STM) support for Coreboot.Amusingly, a big problem during the Cold War era was administrative. NSA's main HQ was at Fort Meade. When that filled up, various auxiliary functions, such as personnel and training, were moved out to Friendship Annex (FANX), near what was then called Friendship Air Terminal, now "Baltimore-Washington International". Working at FANX had less prestige than working at Ft. Meade. Computer security was at FANX. This had a real effect on the effort. Being at FANX meant being on the second team.
NSA had a major downsizing after the collapse of the Soviet Union, and a major rework for the War on Terror. I can't speak to the modern situation. But computer security is still at FANX.