Since that time, the U.S. required a permanent threat to preserve the war economy, which had to be kept intact out of fear of returning to the conditions of the Great Depression.
Presumably this is author's view and the context is after 1973.
Surely this (bold emphasis) part of the sentence is meaningless since it is untrue and anybody could see at that time that economically there were other ways of achieving the same result i.e. not sinking into Depression. What is more true is that oligarchs wanted more for themselves and less for the 99% and not out of any fear about Depression.