Thank you all for taking the time to reply. My original impression was defiantly that the role of the US forces job was to shape the global environment in a way that was best for the US’s economic and political interests and to the detriment of any nation or group that went contrary to those goals. This seemed to fit well with the size and global power projection evidenced by overseas bases and carrier groups. My confusion arose from statements like Ken Whites on the Powell and Weinburger Doctrine
Both were expressly designed to deter use of the Armed forces in anything short of a war of national survival and to avoid any commitment to peacekeeping, nation building or counterinsurgency work.
If this was what was being taught as the role of the military it seemed difficult to square with either the size & disposition of those forces or the way they seemed to be being employed by their political masters.
The listing kindly posted by RTK seems to imply a much wider role than the doctrine.