This is a deeply somber analysis, and well worth the read. In the long run, I would much prefer to see the United States gradually move away the role of global policeman, because I think it’s a bad idea for any country to be that uniquely powerful. But in my ideal world, that’s something that would happen slowly and gently. Sudden, massive disruption seems likely to end in tragedy.

If history is any guide, the next four years are the critical inflection point. The rest of the world will take its cue from the early actions of the new administration. If the next president governs as he ran, which is to say if he pursues a course designed to secure only America’s narrow interests; focuses chiefly on international terrorism—the least of the challenges to the present world order; accommodates the ambitions of the great powers; ceases to regard international economic policy in terms of global order but only in terms of America’s bottom line narrowly construed; and generally ceases to place a high priority on reassuring allies and partners in the world’s principal strategic theaters—then the collapse of the world order, with all that entails, may not be far off.

https://www.brookings.edu/research/the-twilight-of-the-liberal-world-order/