Answer:
The us goverment used the domino theory as a justification for its involvement in the vietnam way. along with its support for non-communist dictator in southern vietnam
Explanation:
Okay, so, just from the top of my head, I think that it is because of the growing belief of "Manifest Destiny" in the nineteenth century. I'm not sure if this is the actual right answer for your question, but I do know that Manifest Destiny was in the nineteenth century and was the widely held belief in the USA that American settlers were destined to expand through out the continent. And I think both the USA and Europe wanted to expand, it was kind of a copetition/conflict they had. This was actually how Canada and Alaska came to be I believe. This was a simple explanation btw. cx
A is correct industrialized nations have a responsible to promote development in poor countries
One way that politics/society is different today as in 1939 is that in 1939 voting wasnt the same for some people, but today everyone has rights to vote. One way that is the same is that males have been president since 1939- today.