Perimetr, the Russian system, is one solution. The USSR decided not to go for launch on warning. Their plan is that, when things get tense, they activate Perimeter. This is sometimes called "The Dead Hand". If the system was enabled, detected nuclear explosions, and there was no way to communicate with higher authority, it would automatically release weapons control to some lower level of authority. Even then, it's not auto launch; there are people in bunkers somewhere who have to make that decision.

Part of the rationale is that this didn't give the leadership of the USSR direct launch authority. They could enable the system, but that didn't cause a launch. It took H-bombs on Moscow plus an enabled system to do that. This provided a safeguard against the leadership going nuts.

The US should have an interlock like that.