Instead, Hoover believed that Roosevelt posed the biggest threat to peace, holding that Roosevelt's policies provoked Japan and discouraged France and the United Kingdom from reaching an "accommodation" with Germany.[243] After the September 1939 invasion of Poland by Germany, Hoover opposed U.S. involvement in World War II, including the Lend-Lease policy.[244] He was active in the isolationist America First Committee.[245] He rejected Roosevelt's offers to help coordinate relief in Europe,[246] but, with the help of old friends from the CRB, helped establish the Commission for Polish Relief.[247] After the beginning of the occupation of Belgium in 1940, Hoover provided aid for Belgian civilians, though this aid was described as unnecessary by German broadcasts.[248][249]
In December 1939, sympathetic Americans led by Hoover formed the Finnish Relief Fund to donate money to aid Finnish civilians and refugees after the Soviet Union had started the Winter War by attacking Finland, which had outraged Americans.[250] By the end of January, it had already sent more than two million dollars to the Finns.