In season 7 a new structure is created called Homeworld Defense with Hammond as its head. This seems to be formed by the US, but must be controlled by a coalition of nations so does this make Hammond sorta like the "President" of Earth and outside of the control of the US? Or what? I don't think it is ever stated but it seems that after season 7 Stargate clearly goes more international which seems to indicate that while the stargate is stationed in the US the program, if not the world of SG is moving more towards a world government.
Other than just these indications are there any explicit details with regards to this?