Both nationalism and isolationism are incompatible with libertarianism. They emanate from the idea that the national collective is the basic moral unit of existence. If either flourishes, individualism and liberty suffer. Individual freedom can’t survive people being subordinated to a mystic national social super organism. Neither can it flourish when individuals limit the scope of their concerns to only their immediate national community. In both cases, the individual person will be faced with sacrificing their interests and rights for the supposed “good” of an alleged national social super organism. The implications for human freedom are that the individual will lose their freedom in relation to how much the “good” of the national collective demands it.
In spite of the above; the major libertarian theorist, Murray Rothbard, once penned a piece advocating peace within the context of the Cold War that began like this:
To begin with, I wish to put my argument purely on the grounds of American national interest.
How strange to see a libertarian couching their argument in terms of collectivist nationalism. What about how peace will benefit countless people on a global scale by saving them from death at the hands of militaristic warmongering? And lead to the conditions for fruitful internationalist alliances amongst the oppressed everywhere. The oppressed no longer feeling the need to look to nationalist states to protect them from aggressive imperialists.
Rothbard later says:
Simply a genuine policy of peace, or, what is the same thing, a return to the ancient and traditional American policy of isolationism and neutrality.
By using a term like isolationism, he is setting the stage for people living in the territory controlled by the American government to collectively concern themselves only with each other. Of course, Rothbard is discussing the isolation of American military power rather than the kind of isolationism that is anti-trade, anti-migration, and anti-exchange of ideas across national borders. It still has bad connotations of only caring about people within your own immediate collective. Libertarian individualism is about rootless cosmopolitanism rather than national borders. It’s about caring what happens to people without distinctions based on the accident of birthplace. This can mean not being neutral as an individual in the context of something like Nazis vs Jews.
Let us not allow opposition to imperialist interventionism to cloud our judgement about events overseas. If a person is being oppressed or unjustly coerced anywhere on the planet, it’s our concern. An injury to one is an injury to all.