Answer:
I think it was not the United States' Manifest Destiny to control all the land from 'Sea to Shining Sea' because despite what nationalist thinkers, philosophers and politicians of the time mentioned, the nations that shared the North American continent with the United States (Mexico, the British, Spanish, French and Russian colonies and the natives) were not backward or uncivilized nations, so America had no moral obligation to "bring civilization" to the entire continent. Thus, Manifest Destiny was a philosophical conception that concealed behind it a purely expansionist and imperialist intention, whose objective was to constitute the United States as the most powerful nation in the world.