The Soviet Union provided material support to Germany in the war effort against Western Europe through a pair of commercial agreements, the first in 1939 and the second in 1940, which involved exports of raw materials (phosphates, chromium and iron ore, mineral oil, grain, cotton, and rubber). These and other export goods transported through Soviet and occupied Polish territories allowed Germany to circumvent the British naval blockade. In October and November 1940, German-Soviet talks about the potential of joining the Axis took place in Berlin. Joseph Stalin later personally countered with a separate proposal in a letter on 25 November that contained several secret protocols, including that "the area south of Batum and Baku in the general direction of the Persian Gulf is recognized as the center of aspirations of the Soviet Union", referring to an area approximating present day Iraq and Iran, and a Soviet claim to Bulgaria. Hitler never responded to Stalin's letter. Shortly thereafter, Hitler issued a secret directive on the invasion of the Soviet Union. Reasons included the Nazi ideologies of Lebensraum and Heim ins Reich