A fence would dramatically increase American safety.  Mexican violence between drug cartels frequently spills over and threatens the lives and peace-of-mind of Americans as well. The Council on Foreign Relations has said that Mexico's levels of violence and lawlessness over the past few years exceed even those in Iraq or Afghanistan.1 That has forced a costly increased police presence in border areas, and even that often proves insufficient to quell the killings. But even if the violent common criminals were somehow suppressed because of stepped up actions by the Mexican government, an easily penetrated border presents a national security threat. The FBI has warned that it is likely that Al Qaeda operatives and other terrorist groups will use the porous Mexican border as a means of infiltrating the country and launching deadly plots against American citizens in future. To prevent the carrying out of attacks, America needs secure borders.  1 McGreal, Chris. "The battle of the US-Mexico frontier."