VDH is correct in saying that America was icolationist ‘when WW2 started’. Yes, America supplied both Britain and later Russia with equipment after Lend-Lease was passed, but Britain had to endure a long year or so before Congress passed Lend-Lease. The supplies from America before then were pretty paltry and often consisted of obsolete equipment. FDR had to proceed slowly in helping Britain because Americans did not want to join the war.
Right. But America has been “isolationist” since its founding to a large degree. George Washington’s warning to Congress in his farewell address is a pretty good indication of a prevailing wisdom even back then.