> But, if you have no national culture which you find important (enough to defend), then another nation will take advantage of that fact.
Modern militaries don't defend cultures - fighting for "American ideals" or because "they hate our freedoms" is just propaganda. Militaries defend assets, territories and wage war for national interests, and their ability to do so is entirely orthogonal to their nation's sense of culture, or lack thereof.
I don't think it's orthogonal though. You can argue which are the true goals of modern war, and I may find myself in agreement with you, but you can't convince people to support a war "for assets"; not unless you convince them those assets mean something to them, their culture, their religion, their patriotism, their way of life, something. So symbolism and the sense of the "group" (culture) remains very important.
What "not wanting a goddamned military invasion" isn't enough of a motivation for defensive military? There is no need to go that abstract for actual defense as opposed to the old Orwellian euphemism in the Department of Defense.
Perhaps, but how many purely defensive militaries do you know of? If a single soldier steps outside the country's borders to do anything but prevent a demonstrable imminent invasion of their country (so peacekeeping, preemptive strikes, fighting terrorism don't count) then it's not a defensive military.
>fighting for "American ideals" or because "they hate our freedoms" is just propaganda
Close... It's a narrative. And without a compelling narrative, no one is going to sweat and toil to make your spreadsheet tracker of assets look pretty.
Those are only the classical tried-and-true narratives. There are always many narratives, and if one of the old ones happens to fail, new ones will rise to take their place.
Modern militaries don't defend cultures - fighting for "American ideals" or because "they hate our freedoms" is just propaganda. Militaries defend assets, territories and wage war for national interests, and their ability to do so is entirely orthogonal to their nation's sense of culture, or lack thereof.