What is meant when critics accuse the united states of maintaining an informal empire? how exactly has the united states asserted its influence informally?

The concept of an Informal empire describes the spheres of influence which an empire may develop which can be said to translate into a measure of influence over a region or country because of the extension of commercial, strategic or military interests of the empire. In these terms, given the great economic and military power the U. S. holds in the world, it can be described as an informal empire.