...I think that there was a distinct wave of apocalyptic thinking in the 1970s. I'm researching North-South relations during this period, and it is clear that many in the North including policy-makers such as Moynihan and Kissinger saw the era in apocalyptic terms: the oil crisis, the defeat of South Vietnam, the 'Zionism is racism' resolution at the UN, the fear that the then 3rd World had been 'lost' all played into this. There seems to have been a real sense that Western civilisation was under peril: neo-Malthusian concerns and old civilisational/race war ideas intersecting with the emergence of the fears of imminent loss of US hegemony that would last until the end of the Cold War. Around this point the idea of the global South as a cauldron of chaos seems to take shape, reappearing in the 1990s in the work of people like Robert Kaplan's 'The Coming Anarchy'.I was interested in this comment because I did some work on North-South relations of the 1970s ... while an undergrad in the '70s. (
Kissinger on North-South relations was a bit of a different story, though, since he eventually came around to offering a package of concessions in response to the Third World's economic demands (for more stable commodity prices, more loans and development aid, and a lot of other things) which didn't satisfy the demands but was an attempt at accommodation; so at least in terms of appearances he was different on these issues from Moynihan. Stanley Hoffmann wrote that Moynihan laid down the tough talk while Kissinger took softer action.
Moynihan's vision of the U.S. and 'the West' standing up against an allegedly ungrateful, somewhat thuggish Third World does fit into a good-vs-evil, quasi apocalyptic, I guess, frame. But I'm not sure whether the "idea of the global South as a cauldron of chaos" goes back to this period. I suppose the neo-Malthusian concerns about resource shortages, population growth, and so on, could be linked to the chaos theme, but my recollection, perhaps wrong, is that Moynihan himself did not emphasize this aspect. (And note too that not all the concerns about resources, population, etc. could be dismissed as neo-Malthusian.) Anyway, Nick L's comment brought a lot of things back...
Coda: The 'North-South dialogue', the main vehicle through which the Third World pressed its demands, sputtered on until around 1981, when it was finished off by the triple whammy of global recession, looming debt crisis and, above all, the advent of the Reagan administration.