The history of all hitherto existing society is the history of class struggles, said Marx, and the present geopolitical development, too, is probably indirectly shaped by it.
Even before America invaded Iraq, Immanuel Wallerstein prophetically wrote: "the use of such force when the conditions of hegemony have already been undermined is a sign of weakness rather than of strength, and weakens the user" ("Iraq: How Great Powers Bring Themselves Down," 1 April 2002).
Why had "the conditions of [US] hegemony" been undermined by then, though? It would have been nice if it had been due to the strength of the working class, but it was largely due to the weakness of workers, in the United States above all (where workers were so thoroughly defeated that they could sustain their living standards only by working more and more and going deeper and deeper into debt), but also in China (whose economy rapidly developed -- and is still developing -- at the cost of greater inequality) and much of the rest of the world (whose savings -- at the expense of the working class -- went into big accumulations of dollar reserves that helped to keep interest rates low and finance the ever rising US debts).
What comes after the US hegemony remains to be seen.