Following 9/11, United States proposals to Canada and Mexico to collaborate in the area of security have grown, primarily to prevent terrorists from entering U.S. territory. The United States signed smart border agreements with both countries in 2001 and 2002, in addition to strengthening cooperative defense accords. In 2005, a new tri-national treaty was signed, the Security and Prosperity Partnership of North America (SPP), in which security and defense matters have begun to be articulated with economic and social elements. This process has been controversial primarily due to conflict between integrationist postures and nationalist postures concerning issues such as security. This document analyzes the strengths and the limitations of this tri-national security agreement.