Every generation brings up its own radicals. There is radicalism from above and below. Radicalism from above has leaders behaving in unexpected ways, inciting domestic or international disorder. Often, people in office insist on law and order as their doctrine as they confront their challenges in the class of the ruled.
In the US, President Donald Trump espouses radicalism from above, encourages rebellion in some states and threatens to send American military into the streets. He sounds like Herbert Hoover sending General Douglas McArthur to disperse the Bonus Army in Washington DC because he feared “Bolsheviks”. Trump, fearing “leftists”, thinks of unleashing his DDT (Department of Dirty Tricks) on Americans for demonstrating against the police killing of George Floyd, a black man.