That is unfortunately no longer realistic. The skills and supply chains needed to produce high-end military equipment are too different. The production lines have to be kept continuously running or else they would take so long to reestablish that in any serious conflict it would be too late.
The problem isn't that the skills and supply chains are fundamentally different but that supply chains for non-military equipment become globalized if not outright off-shored (often to geopolitical rivals) and therefore cannot be counted on in case of a major geopolitical conflict.
Pre-massive-globalization, we had no problem gearing up for WW2. Our industrial capacity was largely in-house. There were some things like rubber that were off-shore, but generally the industrial toolchain was domestically produced.
Nowadays, many domestic industrial producers rely heavily on these (bloated) military contracts to maintain relevance in a globalized industrial setting where the center of gravity for a lot of heavy industry and tool production has shifted to Asia.
I love international trade and I'm skeptical of military spending (and even more so of military adventurism), but this effect should be kept in mind when making trade policy. The military-industrial complex is keeping alive much of our industrial know-how that would otherwise be entirely be off-shored and retired domestically.
The skills and supply chains are just fundamentally different in crucial areas. A prime example is the specialized techniques for welding together thick hull sections of specialized steel alloys to build a complete submarine. There's no equivalent in civilian industry. If that production capability is ever lost due to a long gap in new submarine orders then it would take many years to reestablish. Institutional knowledge if a fragile thing.
One of the benefits of globalization (and the EU) is that it's to everyone's economic advantage to not have a war between trading nations. This maintains supply, reduces costs, and crazily enough - reduces conflict.
You may lose the ability to make widgets because it's easier/cheaper to buy them from another country, but in theory, you make it up by selling them sprockets, and through the overall economic gains.
In WWII it was the domestic auto industry that converted over to building tanks. However today most of the domestic auto manufacturing is for foreign companies like Toyota, while our domestic companies largely manufacture overseas or in Mexico now.
It would be amazing if WWIII broke out and we had to call on Tesla to manufacture tanks.
