In some ways I think the poor design decisions start with making a system of this nature, with this purpose, digital in the first place. With the current state

In some ways I think the poor design decisions start with making a system of this nature, with this purpose, digital in the first place. With the current state of weapons systems, multi-domain tactics, and the technical capabilities of near-peer rivals, or the types of state actors capable of launching a ballistic missile, a massive cyber/electronic attack will almost certainly precede the kinetic weapons wave. Really, I would want a ballistic missile warning system to be as simple, physical, and reliable as, literally, a big button that sets off the warning broadcast over loudspeakers. It is impossible to prepare for every contingency that may arise from an unexpected all-out attack, but the obvious ones with clear solutions should be mitigated.