 Complete the following phrase:  Supplies to the Soviet Union had been sent via the North Cape to Murmansk and Archangel soon after the German invasion but the number of ships available was limited and convoys were vulnerable to German air and submarine attack. Supplies were also sent from American pacific ports to Vladivostok in Soviet-flagged ships but Allied planners wished to open another supply route through Iran. Though officially neutral, the Shah was widely viewed as pro-German by the allies. Following the Shahs refusal to open Iran up as a supply route for war materiel to the USSR; 