The whole idea of the Mandate System which was included in the League of Nations Covenant, transferred later on to the “Trusteeship” system and was actually bluntly stipulated in a unique article in the UN charter. Both concepts are hardly any different. Colonial powers at the time, aka current super powers, thought they have an obligation toward “uncivilized” nations to teach them how to be civilized; by colonizing them.
Basically having authentic cultures that are different from the western culture was considered “uncivilized”. It took a whole system of a “sacred trust of civilization” to get the job done and, of course, several decades of colonization of “savage” territories. The system was only abolished in 1994, with Palau gaining independence from- guess who? the United States of America. But apparently, the rationale behind it is still alive and kicking.
Remember the ‘democratization of Iraq’? It was the second major reason for the US’ invasion of Iraq, after the ‘ weapons of mass destruction’ Saddam Hussein owned, of course. Iraq was a dictatorship, I agree. But this doesn’t automatically legitimize a “corrective” invasion. It is called Aggression in International Law, a crimes that falls under the jurisdiction of the International Criminal Court. Not to mention atrocities and Crimes Against Humanity committed in invaded countries by super powers who claim to have a moral obligation to democratize the world, the uncivilized world. If it was a just world, quite a few famous western leaders would have been brought before the ICC.