DiscoursedRome had a lot of good stuff to add in response to this, but also:
If a nation fails to maintain a sufficiently large core of people who are willing to kill and die for it, it will cease to be a nation. These people must be willing to kill those who, outside of a war, would not deserve it.
For instance, do you think most of the men fighting in the Iraqi Army during the invasion of Kuwait deserved to die? Most of them were there through fear, probably coerced. The same would be true of a Communist invasion. For North Korea, one can argue that even if they’re brainwashed into it, no one deserves to be brainwashed. And sometimes, people that would otherwise be normal will fight to the death during a war out of loyalty or ideology.
That isn’t to say that you can’t do anything about this. The US Army deliberately targeted armored vehicles rather than light infantry and took many prisoners during the first war with Iraq, in part because they knew the men would surrender.
But if some dictator took over Mexico and formed an army of conscripts moving north, bent on human wave attacks, then you have to be willing to kill at least some of them who didn’t deserve to be in a conscript army, or you will lose territory.
Of course, having this capability means having the ability to misuse it, which is why I will never forgive the NeoCons.
There are other things like this as well. There are criminals, terrorists, ideologies with higher numbers of terrorists, foreign agents, dictatorships and authoritarian regimes, elements that would politically undermine democracy, and so on. Then there are incentive problems with open borders, in that if people aren’t at least somewhat glued to a location, they have less incentive to take care of it. There are issues with the fragility of cultures, institutions, and moral norms.
If the entirety of Earth were made up of the LW diaspora this wouldn’t be as much of an issue, but it isn’t.
