In April 1941, the Empire of Japan and the Soviet Union signed a neutrality pact and Japan increased pressure on the Vichy French and Dutch colonies in Southeast Asia to cooperate in economic matters. Following Japan's refusal to withdraw from the Republic of China (with the exclusion of Manchukuo) and Indochina; the United States, Great Britain, and the Netherlands imposed an embargo (July 22, 1941) on gasoline, while shipments of scrap metal, steel, and other materials had virtually ceased. Meanwhile, American economic support to China began to increase.