At it's heart it is a reaction to the social breakdown that comes from capitalism. That reaction draws upon extreme nationalism that can take become pure racism. This is an ancient tribal instinct that has taken the flag-waving nationalist form to fight for control of land, resources & markets for the national ruling classes, probably since the rise of agricultural societies, like feudalism. Capitalism took this nationalism for the same purposes & we got imperialism.
In 1914 we had the collapse of the Second International when the British Labour Party & the German SDP both succumb to this nationalist instinct & sent their respective working classes to massacre one another. British imperialism versus German imperialism. It was the war reparations imposed upon Germany, & so the German working class, that led to the rise of Hitler; along with the fear of working class revolution by the rich & the previously rich middle classes, spreading from Russia. Again the Labour Party & the SDP were active in directing the workers away from revolution.
After WWII & the defeat of fascism, the US empire was established. Not on the basis of overt political colonies, but upon Bretton Woods & economic control. As capitalism continued it broke down society social glue with liberalism. The only thing that matters is money.
Now with capitalism not being able to meet the needs of increasing numbers of workers, largely due to the falling rate of profit from capital accumulation itself, the workers are looking for change, & the middle classes see capitalism works from the multi-nationals & investment bankers but not their small businesses. Hence the rise of the 'libertarian' right who think the corruption can be taken out of capitalism. This is anti-state, or at least the minimal state that is primarily to ensure property 'rights'. It that sense it is different from the 'national socialism' of the Nazis, or even Mussolini's Italy or Franco's Spain, that was a more interventionist state that was above supposedly class divisions; indeed, it was seen as the job of the state, lead by the 'father-figure' to reconcile the class conflict. This meant physically destroying the working class political organisations, whether socialist/communist parties or trade unions, that promoted class struggle. This is the increasing similarity with the 'libertarian' right.
Fascists cannot rescue capitalism beyond restoring the rate of profit through large scale capital destruction, as the two world wars did, along with the Great Depression. But after WWIII there wouldn't be much of capitalism left, let alone life on earth. War is where extreme nationalism & fascism leads. The hatred that comes from scapegoating foreigners ensures that.
It is a critical time in human history. Freedom for humanity can only come from the working class rising up against the rich. They have to do this & set about building a society based upon social/common owner