From a world-systems perspective, it's less strategic incompetence than the inevitable decline phase in a cyclical process of successive hegemonies. The US has simply been overtaken by a more dynamic economic power that it helped to create and continues to foster. The US's "missteps" look quite familiar to historians looking at similar periods in capitalist history. Whether, as in previous eras, this transition will only be cemented after a period of global chaos and war remains to be seen. But it's certainly looking that way.
Again, the late Giovanni Arrighi is a great resource here.