The attacks on the United States of September 11, 2001 changed dramatically the dynamic and nature of North American relations, igniting interest in closer cooperation among the three countries, especially on issues relating to security, border patrol and immigration. This renewed interest in strengthening collaboration in North America has crystallized into a call for the establishment of a "North American Security Perimeter." The three North American countries have taken several significant steps to strengthen collaboration on security matters. In effect, security cooperation within the continent has never been as strong, and it has in fact been institutionalized between Mexico and the US on some levels. Nonetheless, despite this new level of continental security cooperation, this article advances the argument that we are still far from the establishment of an international regime that would resemble anything close to a security perimeter. Instead, it is argued that what we are witnessing is the emergence of an informal North American security system that has unfolded along the two traditional axes that have historically characterized North American relations: the US-Canada relationship and the US-Mexico relationship.
