The Member States of the United Nations have a legal obligation to register treaties and international agreements with the Secretariat. The Secretary-General of the United Nations is the depositary of more than 560 multilateral treaties which cover a broad range of subject matters.International agreements are formal understandings or commitments between two or more countries. An agreement between two countries is called "bilateral," One of the most influential thinkers in the history of liberalism, he contributed widely to social theory, political theory, and political economy.