Pact, which was purportedly directed against the Communist International, though it contained a secret agreement that either side would remain neutral if the other became involved with the Soviet Union. In November 1937, Italy also joined the Anti-Comintern Pact. Late 1930s The Moscow Trials of the mid-1930s seriously undermined Soviet prestige in the West. Soviet purges in 1937 and 1938 made a deal less likely by disrupting the already confused Soviet administrative structure necessary for negotiations and giving Hitler the belief that the Soviets' were militarily weak. The Soviets were not invited to the Munich Conference regarding Czechoslovakia . The Munich Agreement that followed marked the dissolution of Czechoslovakia in 1938 through a partial German annexation, part of an appeasement of Germany. After German needs for military supplies after the Munich Agreement and Soviet demand for military machinery increased, talks between the two countries occurred from late 1938 to March 1939. The Soviet Third Five Year Plan would require massive new infusions of technology and industrial equipment. An autarkic economic approach or an alliance with England were impossible for Germany, such that closer relations with the Soviet Union were necessary, if not just for economic reasons alone. At that time, Germany could supply only 25 percent of its petroleum needs, and without its primary United States petroleum source in a war, would have to look to Russia and Romania. Germany suffered the same natural shortfall and supply problems for rubber and metal ores needed for hardened steel in war equipment , for which Germany relied on Soviet supplies or transit using Soviet rail lines. Finally, Germany also imported 40 per cent of its fat and oil food requirements, which would grow if Germany conquered nations that were also net food importers, and, thus, needed Soviet imports of Ukrainian grains or Soviet transshipments of Manchurian soybeans. Moreover, an anticipated British blockade in the event of war and a cutoff of petroleum from the United States would create massive shortages for Germany regarding a number of key raw materials Following Hitler's March 1939 denunciation of the 1934 German–Polish Non-Aggression Pact, Britain and France had made statements guaranteeing the sovereignty of Poland, and on April 25, signed a Common Defense Pact with Poland, when that country refused to be associated with a four-power guarantee involving the USSR. Initial talks Potential for Soviet-German talk expansion Germany and the Soviet Union discussed entering into an