The United States has exported special nuclear material, including enriched uranium, and source material such as natural uranium under nuclear co-operation agreements. The United States has 27 nuclear co-operation agreements for peaceful civilian co-operation. In order for the United States to engage in civilian nuclear co-operation with other states, it must conclude a framework agreement that meets specific requirements under Section 123 of the Atomic Energy Act (AEA). The AEA also provides for exemptions to these requirements, export control licensing procedures, and criteria for terminating co-operation. Congressional review is required for Section 123 agreements; the AEA establishes special parliamentary procedures by which Congress may act on a proposed agreement. This book discusses the security of United States’ nuclear material overseas.