The United States military is not meant to only defend the US. It was also made to help other countries prevent oppression, violence, and terrorism. One example of how Special Forces plays a role is the Green Beret’s intervention in Bolivia in the 60’s. Smalls Worlds Journal delves into the history and outcome of the relationship between the US and Bolivia.
Source: https://smallwarsjournal.com/jrnl/art/effects-us-armys-special-forces-bolivia-during-ches-foco