What does the "Viet Nam conflict" have to do with capability-based security?
The location of enemy radar sites was very tightly held information, as knowing what we knew could reveal means and sources of information. The actual airstrikes would eventually be known by the destruction of enemy targets. It wasn't possible at the time to have a computer system which could allow the mixing of these levels of secrecy. This meant everything had to be done by hand.
The development of Multilevel Secure systems by the Air Force in the 1970s is a direct result of that experience.
> The development of Multilevel Secure systems by the Air Force in the 1970s is a direct result of that experience.
BTW, this stuff is not just for Air Force folks, either. Multi-level security is the most principled approach around to efficiently mitigate pervasive information-disclosure vulnerabilities like Spectre. The current approach to mitigation has us flushing speculation contexts down the drain even when sensitive info is provably not at stake, which is wildly inefficient compared to what's theoretically possible.