With Nazi Germany not only having conquered most of continental Europe including France, but also maintaining the impression of a Britain facing imminent defeat, Tokyo interpreted the situation in Europe as proof of a fundamental and fatal weakness in western democracies. Japan's leadership concluded that the current state of affairs had to be exploited and subsequently started to seek even closer cooperation with Berlin. Hitler, for his part, not only feared a lasting stalemate with Britain, but also had started planning an invasion of the Soviet Union. These circumstances, together with a shortage in raw materials and food, increased Berlin's interest in a stronger alliance with Japan. German foreign minister Joachim von Ribbentrop was sent to negotiate a new treaty with Japan, whose relationships with Germany and Italy, the three soon to be called "Axis powers", were cemented with the Tripartite Pact of 27 September 1940.