@SgtBlitz:
Neutrality that lasts as long as you don’t attack neutral powers. (Otherwise, what’s point of neutrality, unless you like jumping the gun?) In 1940, the USA wasn’t at war with either Japan or Germany, and didn’t really want to go to war either.
The above statement is not fully accurate. The American people felt disillusioned by their experience in WWI. (Which they had been told was a war to make the world safe for democracy, but which turned out to be a war to make the world safe for France to exploit Germany.) They were, accordingly, deeply isolationist, when just a generation later the idea was tossed around of once again going to war against Germany.
But America’s elites–most especially including FDR–strongly favored war with Germany. The media was also becoming pro-war; and that became more pronounced as media consolidation occurred. Between the influence of a pro-war administration, a pro-war media, and other pro-war elites, it is probable that even without an Axis attack, America would have gradually drifted into war, much as it had in WWI. By 1940, the U.S. Navy was already participating in joint search and destroy missions against German submarines.
London, by the end of June 1940 was expecting delivery from the United States of no less than 10,800 aircraft and 13,000 aero-engines over the next eighteen months. This was in addition to the Britain’s own production of 15,000 military aircraft. At the same time, the British Ministry of Aircraft Production was negotiating with the Americans to order many thousands more. By way of comparison, total German aircraft production came to only 10,826 aircraft and in 1941 it expanded to only 12,000, a disappointing increase which we will discuss in greater detail below. In addition, there was America’s own gigantic rearmament programme, which tilted the balance even further against Germany. In fact, so large were the combined demands of the British and American programmes that they stretched even America’s industrial resources. But the United States did not respond by seeking to restrict British purchases; quite the contrary. On 23 July 1940 British procurement agents in Washington were invited to a clandestine meeting with American industrial planners, from which emerged a scheme to expand the capacity of the United States aircraft industry so that it would be able to deliver no less than 72,000 aircraft per annum, guaranteeing a supply to the British of 3,000 planes per month, three times the current German output.
Adam Tooze, The Wages of Destruction, 405 - 407
Even though the United States was still technically at peace with Germany in 1940, the former nation’s industrial might was already being put to work to crush the latter.