mid-1930s, the Soviet Union made repeated efforts to reestablish closer contacts with Germany. The Soviet Union chiefly sought to repay debts from earlier trade with raw materials, while Germany sought to rearm, and the countries signed a credit agreement in 1935. The rise to power of the Nazi Party increased tensions between Germany, the Soviet Union and other countries with ethnic Slavs, which were considered "untermenschen" according to Nazi racial ideology. The Nazis were convinced that ethnic Slavs were incapable of forming their own state and, accordingly, must be ruled by others. Moreover, the anti-semitic Nazis associated ethnic Jews with both communism and international capitalism, both of which they opposed. Consequently, Nazis believed that Soviet untermenschen Slavs were being ruled by "Jewish Bolshevik" masters. Two primary goals of Nazism were to eliminate Jews and seek Lebensraum ("living space") for ethnic Aryans to the east. In 1934, Hitler spoke of an inescapable battle against "pan-Slav ideals", the victory in which would lead to "permanent mastery of the world", though he stated that they would "walk part of the road with the Russians, if that will help us." Despite the political rhetoric, in 1936, the Soviets attempted to seek closer political ties to Germany along with an additional credit agreement, while Hitler rebuffed the advances, not wanting to seek closer political ties, even though a 1936 raw material crisis prompted Hitler to decree a Four Year Plan for rearmament "without regard to costs." In the 1930s, thanks to two Foreign Office cipher clerks, namely Ernest Holloway Oldham and John Herbert King, who sold the British diplomatic codes to the NKVD, the Soviets were able to read British diplomatic traffic. At the same time, the Soviet code-breakers were completely unable to break the German codes encrypted by the Enigma machine. The fact that Soviet intelligence-gathering activities in Germany were performed through the underground German Communist Party, which was full of Gestapo informers, rendered most Soviet espionage in Germany ineffective. Stalin's decision to execute or imprison most of the German Communist emigres living in the Soviet Union during the Great Terror finished off almost all Soviet espionage in the Reich. Tensions grew further after Germany and Fascist Italy supported the Fascist Spanish Nationalists in the Spanish Civil War in 1936, while the Soviets supported the partially socialist-led Spanish Republic opposition. In November 1936, Soviet-German relations sank further when Germany and Japan entered the Anti-Comintern