And, shortly after Pearl Harbor, the Germans declared war on the US. If he hadn’t done that, FDR might have had an issue on his hands...
Of course, we’d been waging war against the Germans in the Atlantic since late 1940 or so.
Although the war began with Nazi Germany’s attack on Poland in September 1939, the United States did not enter the war until after the Japanese bombed the American fleet in Pearl Harbor, Hawaii, on December 7, 1941.
Germany and Italy declared war on the United States three days later. The first planned offensive action by the United States in World War II came in January 1942 when the aircraft carrier USS Enterprise attacked Japanese bases in the Marshall Islands.