By the late 1930s, because a German autarkic economic approach or an alliance with Britain was impossible, closer relations with the Soviet Union were necessary, if not just for economic reasons alone.[1] Germany lacked oil, and could only supply 25 percent of its own needs, leaving Germany 2 million tons short a year and a staggering 10 million tons below planned mobilization totals,[25] while the Soviet Union was required for numerous key other raw materials, such as ores (including iron and manganese), rubber and food fat and oils.[25][68][69][70] While Soviet imports into Germany had fallen to 52.8 million Reichsmarks in 1937,[5] massive armament production increases and critical raw material shortages caused Germany to turn to reverse their prior attitude, pushing forward economic talks in early 1939.[71]