During World War II the United States emerged as a major player in Chinese affairs. As an ally it embarked in late 1941 on a program of massive military and financial aid to the hard-pressed Nationalist Government. In January 1943 the United States and Britain led the way in revising their treaties with China, bringing to an end a century of unequal treaty relations. Within a few months a new agreement was signed between the United States and the Republic of China for the stationing of American troops in China for the common war effort against Japan. In December 1943 the Chinese Exclusion Acts of the 1880s and subsequent laws enacted by the United States Congress to restrict Chinese immigration into the United States were repealed.