Ultimately, the Secretary of War rejected mass production of the M1928, citing excessive acquisition costs. Embittered, Christie felt he was justified in selling his inventions to the highest bidder. He began looking to foreign governments to purchase his advanced chassis and suspension systems; Poland, the Soviet Union and United Kingdom had all expressed interest in the designs. A long and complex series of exchanges between Christie and foreign governments followed. These were technically illegal, since Christie never obtained approval of the US Department of State, Army Ordnance, or the Department of War to transfer his designs to potentially hostile governments.