According to Vladimir Petrov in "Money and conquest: allied occupation currencies in World War II" the reason for the change in US occupation policy was almost exclusively based on economic considerations. Although a large part of the occupation costs were placed on the German economy, the US and the UK were increasingly forced to supply food imports to prevent mass starvation. According to some historians the US government abandoned the Morgenthau Plan as policy in September 1946 with Secretary of State James F. Byrnes' speech Restatement of Policy on Germany. Others have argued that credit should be given to former US President Herbert Hoover who in one of his reports from Germany in 1947 argued for a change in occupation policy, amongst other things stating: