Much of today’s far-right political activity is rooted in ongoing decolonization. For poorer, less educated people especially, the principal source of self-validation has often been the association with, within society, white equality, and in an international context, the dominance of that society over other societies.
It helps to think in terms of “civilizations,” which is how the right itself speaks. In the terms of the right, there are clear, distinctly separable civilizations, and they can be listed in terms of superiority. There is “Western” civilization, which has certain inherent identifiable characteristics that make it cleanly distinct from “African civilization,” and these characteristics make it superior to African civilization.
The great wave of decolonization after the 2nd World War forced Europeans to come to terms with Africans (and others) in ways they had never done before. Though their relations were and are not equal, there was at least in principle the idea that Westerners could no longer impose their will on Africans with such ease, and more importantly, with such justification. James Baldwin argues for example that this international shift was elemental to the Civil Rights Movement in the US.
To move to more recent events, I think Iran is a deeply instructive example. The first contemporary radical nationalist president of the US was Ronald Reagan, who came to power amidst the Iran-hostage crisis and the aftermath of the Iranian revolution. In contrast to the weak, internationalist Carter, Reagan was imagined as a reassertion of the ability (and the right) of the US (and by extension Western civilization) to impose its will on unruly groups of non-Westerners (namely brown people, but also other people of color). Indeed, the Iranian revolution itself represented an enormous failure of Western domination, as does the continued opposition of Iran to Western interests.
This I believe helps explain why the Iran deal became such a target of the nationalist right in the US. The deal represented a sort of acknowledgement that Iran could not simply be told what to do. They had to be dealt with, if not as practical equals, as equals in principle, legitimate parties to a multilateral agreement, and not–as hoped by the far right–docile and grateful recipients of greater Western wisdom.
The new internationalism of the world represents therefore, an assumption intolerable to the nationalist right: that the world be morally as well as practically multilateral. Not only are Westerners no longer practically capable of simply ordering everyone around, but neither do we have the right to, which shocks the need of nationalists to associate with a morally superior civilization.
In addition, the turn away from international cooperation represents a kind of losers’ pretense: I am not being forced away from my role as international arbiter of truth and goodness. I remain that in principle. I am choosing rather, to let you all burn in the absence of my superiority. That makes the loss of my superiority my choice and your loss, rather than your choice and my loss.