 The British , for their part , wanted to block the flow of iron ore from Swedish mines to Germany because the Swedes supplied up to 40 % of Germany 's need . The matter was raised by the British Admiral Reginald Plunkett on 18 September 1939 , and the next day Winston Churchill brought up the subject in the Cabinet . On 11 December , Churchill opined that the British should gain a foothold in Scandinavia with the objective of helping the Finns but without a war on the Soviet Union . Because of the heavy German reliance on Swedish iron , Hitler had made it clear to the Swedish government in December that any Allied troops on Swedish soil would immediately provoke a German invasion . 
