Actually the conception was at least as old as Henry Luce's essay in LIFE Magazine of February 7 1941 entitled "The American Century" (10 months prior to Pearl Harbor).
"The other day Herbert Hoover said that America was fast becoming the
sanctuary of the ideals of civilization. For the moment it may be
enough to be the sanctuary of these ideals. But not for long. It now
becomes our time to be the powerhouse from which the ideals spread
throughout the world and do their mysterious work of lifting the life
of mankind from the level of the beasts to what the Psalmist called a
little lower than the angels."
Of course that sounds a lot like the othery Henry, Henry Labouchère:
Pile on the brown man's burden,
compel him to be free;
Let all your manifestoes
Reek with philanthropy.
And if with heathen folly
He dares your will dispute,
Then, in the name of freedom,
Don't hesitate to shoot