The purpose of this study was to examine the responses of the US to three nuclear weapons free zone agreements as an example of international cooperation and security regimes. The agreements included were the Treaty of Tlatelolco (Latin America and the Caribbean), the Treaty of Rarotonga (South Pacific), and the Pelindaba Treaty (Africa). Seven hypotheses and seven focus questions were developed with the aid of Putnam's (1988) theory of two-level games, to analyze the treaties and how the US responded to those treaties. As expected, the three factors that were not included in the list of seven criteria outlined by Blaz (1987) were important in determining how the US responded to the NWFZ agreements. Responses of other nuclear weapons states such as Russia and France were important factors. Another important factor was the presence of the Nuclear Nonproliferation Treaty within the international environment. The third pair of important factors, that could be examined more closely, were the parties that have been in power in both the presidency and the Senate since these agreements were created.