I totally agree with your example, but I don't see that need for modern manufacturing for national defense. Our defense manufacturing is greater than any other country already because it has always been domestic. We are the preeminent defense manufacturer and just halting our exports would double our inventory. And back in WWII, Ford needed to retool to build aircraft because, well, there was no aircraft industry then. Just think how many fighters Boeing could produce on their massive lines when they no longer needed to build commercial jets. Or all the numerous smaller plane manufacturers like Lear or Gulfstream. And we don't need to even mention the advantage we hold in the number of firearm manufacturers.
But even using the automobile manufacturing as the example since that is where the tariffs are aimed, we are already the second highest producer of vehicles in the world, second only to China. But the big advantage we have is that we are number one in the world for commercial vehicle manufacturing, which would be the most helpful in time of war. Over twice the number that China builds.
Honestly, when considering national security concerns with trade, a very good friendly relationship would probably be better than pissing off your neighbor with a tariff. When another country needs to pick a side, you want them to pick yours.