Denmark was occupied by Germany after April 1940 and never joined the Axis. On 31 May 1939, Denmark and Germany signed a treaty of non-aggression, which did not contain any military obligations for either party. On April 9, Germany attacked Scandinavia, and the speed of the German invasion of Denmark prevented King Christian X and the Danish government from going into exile. They had to accept "protection by the Reich" and the stationing of German forces in exchange for nominal independence. Denmark coordinated its foreign policy with Germany, extending diplomatic recognition to Axis collaborator and puppet regimes, and breaking diplomatic relations with the Allied governments-in-exile. Denmark broke diplomatic relations with the Soviet Union and signed the Anti-Comintern Pact in 1941. However the United States and Britain ignored Denmark and worked with Henrik Kauffmann Denmark's ambassador in the US when it came to dealings about using Iceland, Greenland, and the Danish merchant fleet against Germany.