Although the Lend-Lease Act strictly adheres to the technical definition of neutrality, everyone in positions of power around the world understood it as a highly charged act, tantamount to saying, "This means war."
The unprecedented American industrial economy was about to be supercharged and transformed into, as FDR called it, "the arsenal of democracy." Yeah, the word "arsenal" sounds warlike to us, too.
Modern warfare was total and involved the entire economy.
Postmodern warfare isn't declared.
Technically speaking, the United States could have entered World War II earlier. But public opposition made it politically impossible.
Much of this can be attributed to admirable hope for peace and a disdain for war. But some of this can also be attributed to a somewhat less admirable, though understandable, fear of "getting involved" in a world war in which the entire planet was already irreversibly "involved."
Tyranny of all kinds must be checked at all times by anyone who can in order to avoid what would otherwise be inevitable catastrophe.
Engaging in passivity (when it's possible to "do nothing" or at least to not do some things), can leave you in a stronger position in the end.
WWII is often portrayed in popular culture (and political culture) as the most clear confrontation of good and evil, with good often being the United States and the United Kingdom, evil being the Nazis, Italians, and Japanese, and somewhere in between being the Soviet Union.
Other portrayals attempt to humanize the individual soldiers and citizens who were caught up in the various totalitarian regimes, supporting the viewpoint that Evil with a capital E is something of a fiction. However, Eichmann in Jerusalem: A Report on the Banality of Evil, a famous intellectual book by Hannah Arendt, talks about how the Nazi atrocities were carried out by bureaucracies with lots of paperwork and chains of workers who were "only doing their jobs."
The Lend-Lease Act doesn't explicitly discuss the question of good and evil, but as its official title is "An Act to Promote the Defense of the United States," it certainly assumed there was something out there the United States needed to defend itself from.
Regardless of the ethical complication of war, evil is easy to identify in situations where human beings are oppressed by dictatorial regimes.
The victor of any conflict determines, to some degree, who is right and who is wrong, making clear cut decisions about what is good and what is evil difficult to discern.