Border Security: Observations on Costs, Benefits, and Challenges of a Department of Defense Role in Helping to Secure the Southwest Land Border, Statement of Brian J. Lepore, Director, Defense Capabilities and Management Issues, Testimony Before the Subcommittee on Border and Maritime Security, Committee on Homeland Security, House of Representatives [open pdf - 227KB]
"DHS [Department of Homeland Security] reports that the southwest border continues to be vulnerable to cross-border illegal activity, including the smuggling of humans and illegal narcotics. Several federal agencies are involved in border security efforts, including DHS, DOD [Department of Defense], Justice, and State. In recent years, the National Guard has played a role in helping to secure the southwest land border by providing the Border Patrol with information on the identification of individuals attempting to cross the southwest land border into the United States. […] This testimony discusses (1) the costs and benefits of a DOD role to help secure the southwest land border, including the deployment of the National Guard, other DOD personnel, or additional units; (2) the challenges of a DOD role at the southwest land border; and (3) considerations of an increased DOD role to help secure the southwest land border."
Government Accountability Office: http://www.gao.gov/