As demonstrated by the events of September 11, 2001, it only takes a dedicated few to execute a serious attack on the United States (US) within its borders. An armed invasion can now arrive in the form of a weapon of mass destruction (WMD) employed by a few dedicated "soldiers" dressed in plain clothes. The US must be able to prevent WMD and terrorists from entering the country. This requires being able to effectively screen all goods and persons entering the US. Although seaport security is equally as important, the focus of this paper will be on the effort to secure the US land borders. Since human and contraband smuggling occur on a much larger scale along the southern border than the northern border, we will further limit our attention to the effort to secure the US border with Mexico.