US soldiers during the post WW2 era are overwhelmingly deployed for non-directly aggressive purposes in fact. They're deployed as a standing deterrent to regimes looking to conquer other nations.

That includes in Japan, South Korea and various nations in Europe (Germany, Italy, Poland, et al.). By the hour, those locations have seen the largest and longest-term US military deployments in its history. They're not there to start wars, they're there to deter the aggressors (Russia, North Korea, China primarily) from attempting to conquer their neighbors and annex more territory.