America - World sheriff?

Please don't perceive this thread as a dig.
I believe, as does most of the world, that N. America's military might puts them in a position as world-sheriffs.
China is more concerned with its 'own' intercommunal' agenda, Russia, with resource-monopolies and, the arabs, with cultural-divides......... etc.

My question is - Do you believe that those who direct the 'world-sheriff/police/mercs, whatever.... Have ever done so - For the benefit of 'other than their own agenda/for the people/for YOU'?

Just after a geocentic insight here guys.
Cheers!