The country's foreign economic relations have been conditioned by its leadership's economic goals and political persuasion. As a poor, undeveloped country intent on modernizing and expanding its economy at a rapid pace, Albania has had to rely heavily on foreign economic and technical assistance during the post-World War II period. The leadership's extreme Marxist orientation and hostility toward the Western nations have precluded a recourse to non-Communist sources of aid and have made the country entirely dependent upon contributions by other Communist states. But even within the Communist sphere political disagreements have had a disruptive effect on aid arrangements (see ch. 6, Government Structure and Political System). From 1945 to 1948 economic and technical assistance was received from Yugoslavia. After the political break between that country and Albania, the Soviet Union assumed the role of major aid donor, and smaller contributions were made by some of the East European Communist states. Since 1961, when the substantial support of the Soviet Union was lost in the wake of the political schism within the Communist world engendered by the Sino-Soviet dispute, Albania has been able to obtain assistance only from the People's Republic of China (Communist China). The readjustment necessitated by the abrupt withdrawal of all Soviet aid and technical advisers was said by Albanian leaders to have retarded economic development by three years. The extent of aid received in the form of long-term loans, some of which became grants through debt cancellations, is only partially known. The amount of total loan commitments by the Soviet Union in United States dollar equivalents for the period of 1945 through 1961 was estimated by one Western source at US$246 million. Another Western source reported the amount of loans promised by the Soviet Union and the East European Communist states for the 1961-65 period to have been in excess of US$132.5 million. These loans were cancelled in their entirety in the spring of 1961. A partial list of Soviet loan commitments, compiled by a Western student from Soviet economic literature, totaled US$172 million for 1957-61. The actual amount disbursed, however, was much smaller. Aid deliveries, as reflected in official Soviet statistics, totaled only US$39.4 million for the years 1955-61. Similar information on aid deliveries from 1949 to 1954 was not readily available. Western observers believe that the economic crisis created by the Soviet withdrawal of aid forced Albania to default on the outstanding loans.