alt Hacker NewsSome would dispute the "downward" part there.
Not trying to be the world's policeman would allow tremendous downsizing of the military and its associated expense.
Decoupling and isolation is a very rational response if nuclear proliferation is going to accelerate, in order to avoid having entangling alliances pull the country into a nuclear equivalent of the first World War.
"World's policeman", that's what you tell little kids America was doing. America didn't invade Iraq or Afghanistan for world peace. There were strong economic and strategic motives behind those invasions.
At the same time, soft power is also vanishing.