Metus hostilis /fear of the enemy/ is always the deepest trigger for governments’ policies in all countries at all times, especially for the American Empire /Janan Ganesh, FT, 17 February 2021/. When it comes to the U.S., indeed, wars had been forging the ever-larger and stronger world power.
Nevertheless, you need two different strategies for building up and maintaining an empire. Wars proved to be instrumental to create the empire, but they can be detrimental to it when you are on the top.
Instead, you’d better use the other major piece of Roman advice to avoid a major war. The policy of “Divide et impera” is definitely better than waging a risky war.
Besides, empires and world powers finally vanished, but some smart nations survived. The ancient recipe for survival is “to live and let live”.