ABSTRACT
The obligation that states have to obey established rules of international law is the most basic obligation of states under international law. This fundamental norm constitutes the sine qua non for effective international law. It reflects and gives legal expression to the common interest shared by all states in an effective international law system. At the root of many of the difficulties hindering Soviet-US relations in past years have been fundamentally conflicting perspectives on issues of world order, the rule of law, and the nature and role of the State—including respect for the rights of individuals. Relations between and among States are governed, in general, by rules and principles established by treaty and by customary international law. Arguably the most fundamental of all such principles is the maxim pacta sunt servanda (“agreements are to be obeyed”), which reflects the obligatory nature of the modern international system. Treaties and other international agreements provide a major source of international obligation.
