All German strategies before and during the Second World War were conditioned by the position of Germany, like its predecessor Prussia, in the middle of Europe. Over several months, Adolf Hitler sent the German navy and air force, both carrying troops, to occupy Denmark and Norway in April 1940. The new plan reduced emphasis on the Atlantic ports, probably in view of the occupation of Norway, and instead placed the emphasis on the left or southern thrust through the Ardennes to the channel, on the correct assumption that the British and French would send troops to assist the invaded countries. The defeat of the Soviet Union would encourage Japan to move in East Asia and keep the United States preoccupied there until Germany was ready to fight and defeat that country. Hitler personally promised Japanese foreign minister Matsuoka Yosuke, that Germany would declare war on the United States when Japan did, and the Japanese received similar assurances from Benito Mussolini.