In recent years, American treaty behavior has produced growing concern among both allies and less friendly nations. On such fundamental issues as nuclear proliferation, terrorism, human rights, civil liberties, environmental disasters, and commerce, the United States has generated confusion and anger abroad. Such a climate is not conducive to needed cooperation in the conduct of foreign and security policy. Among U.S. actions that have caused concern are the failure to ratify several treaties, the attachment of reservations, understandings, and declarations before ratification, the failure to support a treaty regime once ratified, and treaty withdrawal. The structural and historical reasons for American treaty behavior are deeply rooted in the United States' system of government and do not merely reflect superpower arrogance.