Why do we even use the same physical network for national defense that we use for everything else? Even the hacks on cars or the electrical power grid suggest the need for parallel networks with physically controlled access points. What the hell are these people thinking?
There are multiple networks. DoD uses a very different network than the OPM. However agencies need to communicate with each other.
The solution isn’t really creating parallel networks as that increases the over complexity and cost dramatically. The solution is to follow the damn rules.
This was almost certainly avoidable if they followed the rules and built their systems properly.