How did the United States respond to war in Europe before Pearl Harbor?

Though FDR and a number of other leading American politicians were profoundly sympathetic toward the plight of Europeans, isolationism remained the dominant attitude in the United States. World War II was regarded as a European war; it was a conflict in a faraway continent that had nothing to do with the United States. America had found itself embroiled in a European war less than a quarter of a century before, yet Europe was now more unstable than ever. If the United States could not bring long-term stability to Europe in World War I, asked isolationists, how they could possibly do so now?
A series of Neutrality Acts passed by Congress prevented the Roosevelt Administration from actively getting involved in the rapidly spreading European conflagration. For his part, FDR tried to water down isolationist legislation, but the official policy of his administration remained one of formal neutrality. However, slowly but surely, Roosevelt offered more and more support to Great Britain in terms of materiel. The Lend-Lease program was particularly crucial in this regard, allowing the British and other European allies to gain greater access to American arms and supplies.
The decision by FDR to send American Navy vessels to the North Atlantic to patrol the sea and to escort British ships meant that the United States was at war with Nazi Germany in all but name by the spring of 1941. By the time the Japanese finally attacked Pearl Harbor, the ground for the United States' involvement in World War II had already been prepared to a considerable extent.
https://millercenter.org/president/fdroosevelt/foreign-affairs