Also it reminded me of Yossarian's argument in 'Catch-22': the enemy is whoever is trying to get you killed. In his case it was more often the generals sending him on suicidal bombing missions than the actual combatants on the other side. Stalin's Order 227 during the battle of Stalingrad commanded the formation of 'blocking detachments' the function of which was to shoot 'panic-mongers and cowards' who didn't want to follow the 'not one step back' directive to their deaths - https://en.wikipedia.org/wiki/Order_No._227 I've read testimony from Russian soldiers saying that this was what they needed at the time to close off any thought of retreat or surrender, but I can't imagine how someone could see that happening and still maintain a love of their country, unless it was completely divorced from the political and economic governing structures that dominate it.
To be honest if the Russians or the Chinese invaded the UK I don't think I'd lift a finger to oppose them, unless there was a direct threat to people or places I hold dear or it looked like they were going to institute a worse regime than the current one in power, as hard as that is to imagine at this point in time... The Enemy for all my life has been the UK government and the planet-murdering, soul-sucking cancer of corporate capitalism & empire it represents. They're the ones trying to get me killed - why the f* would I fight to save that? Yet I'm sure thousands would queue up at the army recruitment offices at the merest hint of a threat, so effective is the nationalist propaganda we're subjected to...
It's a toxic mimic of tribal identity: humans evolved in the context of small hunter-gatherer bands of no more than a few hundred people. It would make sense to defend your tribe to the death in that situation, because that was your vehicle for survival and your whole identity, the repository for all the cultural stories, traditions, local know-how and guidance for how to handle everyday affairs. It makes sense to fight to protect & preserve a system that serves you and makes your life better. Nation-states use this tendency to justify taxes, endless hours of labour and to recruit cannon fodder for their expansionist resource wars, but it's perverted because they fail to live up to their side of the bargain. We 'serve' it again and again, even giving up our lives in the process, but only end up being further exploited for our troubles. Jensen put it best:
But, as you suggest, that's not to stand in judgement of how oppressed people choose to bind themselves together in resistance, which is often behind a flag or some religious dogma. If it serves them, fine. At some point that will probably no longer apply though, and they'd likely be better off ditching it.