A global military presence has allowed the US to exert influence throughout the world. It's a pretty interesting (and controversial) topic, but I recommend read

A global military presence has allowed the US to exert influence throughout the world. It's a pretty interesting (and controversial) topic, but I recommend reading up on American imperialism[0], and the argument that the military base is modern America's version of a colony. We don't maintain a military presence in Europe because they're incapable of defending themselves, we maintain a presence because it grants us influence in Euro politics. [0]: https://en.wikipedia.org/wiki/American_imperialism https://en.wikipedia.org/wiki/American_imperialism