Why did the us want to be neutral during ww2?

Simply because war is something that as a nation, you don't want to get into.
People die, and you have to spend enormous amounts of the country's money
on things that just kill people and don't produce anything.

But it became pretty tough to remain neutral when Japan destroyed the US
naval base at Pearl Harbor in Hawaii, on December 7, 1941.

Photographs of soviet missiles from 1950