That one needs emphasising.
As well as providing organising space on their websites, the American right also promotes extremism more directly.
Almost all of the right wing bastards in Australia are at least partially funded from the USA. Partly via the actions of American right political activists, partly via the actions of the US government.
The USA has been funding and promoting right wing extremism across the globe for seventy years. Long before Daesh radicalised anyone, the US government radicalised many.