I don't have a clue about the answer, so this is semi-rhetorical, but what raw materials do they depend upon? What don't they possess and how hard is it to ramp up production if needed?
Anyway, you'd also have to spread your shops around the country as the Japanese discovered during WWII. Fun fact: XX Bomber Command almost ran out of napalm and the US had to go to some extraordinary lengths to resupply the B-29's with fire juice.
Other problems with distributed manufacturing are cost and the all important logistics. Great, you've spread out your assets and it is very difficult to degrade your manufacturing efforts. Do you have the trains and trucks to move the stuff? The US strategic bombing campaign didn't really pay dividends until A) P-51s showed up and B) they switched to rail yards and bridges (though the latter was usually a medium bomber problem and less than effective).
"But what about the Ho Chi Minh Trail?" Eh, not the same. Modern nations require modern logistics. Shut down some bridges, interstate overpasses, interstate junctions like I-95 and I-10, regional truck yards (some of those terminals are massive) and now you can make all you want, but you can't deliver. That goes for raw materials and the finished product alike.
Another fun fact and then I'll stop because you're all probably bored: Get a Masters in Logistics and you become sought after by intel agencies. Why? You know how to compute throughput based on factors like roads, bridges, etc., plus a whole host of other things related to shipping. In the 90's I worked with a guy whose brother did just that from the University of Maryland. Dude graduated and started at the CIA at their next pay cycle.