This work is limited to South America. Its purpose is to demonstrate that the proliferation of small arms widely promotes asymmetrical threats, also called new threats. It initially addresses the present world situation, which is considered to include the concepts of globalization and transnationalization, taking the events of September 11, 2001 as a fundamental milestone. It then analyzes the concept of threat as it affects international security; the need to extend the strict application of the concept of defense to that of national security; the meaning of protection, of asymmetry and related concepts; and the involvement of small arms, particularly illegal ones. It analyzes the interrelationship between asymmetrical threats on the basis of leading cases in this issue. Colombia and its "gray areas" is one case considered and the work goes on to address the relationship between these threats and small weapons. It includes an analysis of the concepts of arms, a combined look at the evolution of the international situation in small arms, their illegal trade and leading cases in the link between new threats and weapons in Bolivia, Brazil and Colombia. The work closes with partial conclusions concerning the State's position with regard to small arms and asymmetrical threats and offers a general, broad conclusion on the issue, confirming the stated objective.