This is a difficult question, even for experienced diplomats! Lately, this issue has been complicated only by the terminology suggested by the famous publicist Anthony Aust, author of the law and modern advocate of the treaty. However, it is possible to explain the situation as follows: it is a “paper” between states. Let us call these documents or documents “instruments” (not “agreements”). Some of these instruments should create obligations and obligations in international law under international law; while others only need to clarify intentions and decisions that are political in nature but not legally binding. The first type of document is in fact called a “contract” under the terms of the 1969 Vienna Convention on Treaty Law: The U.S. Supreme Court has ruled in the spirit of money cases that “contracts” have no privileged position in relation to the acts of Congress and can be nullified or amended under U.S. law. , by any subsequent congress legislation, like any other regular law. The court also tried in Reid v. In a covert way, that the provisions of the treaty that are in conflict with the U.S.
Constitution are null and void under U.S. law.  A party may argue that a contract should be terminated, even without any express provision, if the circumstances have fundamentally changed. Such an amendment is sufficient when it is unforeseen, undermines the “essential basis” of a party`s agreement, radically alters the scope of commitments between the parties, and the commitments have yet to be fulfilled. A party cannot base this assertion on changes induced by its own breach of contract. Nor can this statement be used to invalidate contracts that have set or redefine political boundaries.  International agreements are formal agreements or commitments between two or more countries. An agreement between two countries is described as “bilateral,” while an agreement between several countries is “multilateral.” Countries bound by countries bound by an international convention are generally referred to as “Parties.” An interpretive statement is a statement by which a state determines the meaning it attributes to a provision of the treaty.