Intuitively it sounds quite sensible. The more a nation can sustain itself on its internal market, the longer they can hold out through negative external circum

Intuitively it sounds quite sensible. The more a nation can sustain itself on its internal market, the longer they can hold out through negative external circumstances. Much like energy. When everything is going rosy, relying on high % imports can be economically beneficial. In the case of extreme events like local or global wars, it leaves the country extremely fragile. Even outside wars, if there are drastic price increases in the global market then you are highly exposed. Look at OPEC, the power they wield and how they direct their efforts in essentially geo-political 'battles'. I don't know much about it, but I suspect that energy and agricultural self-sufficiency are very important and underestimated factors in (developed) nation state security.