The declaration of war upon Germany by the British in September 1939 forced a break in liaison between SIS (MI6) and the FBI because of the Neutrality Acts of 1930s. William Stephenson was sent to the US by the head of SIS to see if it could be rekindled to an extent that SIS could operate effectively in the US. While J. Edgar Hoover was sympathetic, he could not go against the State Department without the President's authorisation; he also believed that if it was authorised, it should be a personal liaison between Stephenson and himself without other departments being informed. However, Roosevelt endorsed co-operation.