B. Nazi Germany and the Axis power
The American President Franklin Rooselvelt made such claim in his "The Great Arsenal of Democracy" speech, delivered on 29 December 1940, in the middle of the World War II (1939-1945).
In the speech, Roosevelt emphasizes that the aggressor nations of Nazi Germany and the Axis power undoubtedly represented a threat to American society, and thus, America had a duty to help Britain fight the Axis by giving them military supplies while it stayed out of the actual fighting.
The President stated that If the Axis won the war, they would take over other continents nearby (Asia, Afria, Europe) and would bring enormous military and naval resources against America as well, as he stated:
(...) all the Americas would be living at the point of a gun -- a gun loaded with explosive bullets, economic as well as military. We should enter upon a new and terrible era in which the whole world, our hemisphere included, would be run by threats of brute force. And to survive in such a world, we would have to convert ourselves permanently into a militaristic power on the basis of war economy.