In the last generation we've moved past a U.S.-Mexico relationship that while friendly on the surface, and demilitarized for the most part, really was not a genuinely cooperative relationship. As a result of the U.S.-Mexico War in the 19th century, and the treaty of Guadalupe Hidalgo in 1848, half of what was Mexico was severed and became much of the western part of the United States. To add insult to injury, most Americans never knew that, and most Mexicans have never forgotten it.

The idea was to restore the rule of law, to bring order to a chaotic situation. The results became more and more apparent. Crime rates went down in the border region. Today, the number of migrants crossing is at a 30-year low. That's because of years of bipartisan work on this issue.

Not only are the numbers of migrants entering the United States at the lowest levels in a generation, but they are now largely Central American. Four out of five border-crossers detained in South Texas are Guatemalan, Honduran or Salvadoran. They are driven by violence and poverty in their home countries and the desire for family reunification.

The image and the costs of a Berlin-like wall or a Great Wall of China is something that the American people have not accepted to date.

Homeland security is inherently transnational today. There's hardly anything adverse that happens in our homeland that doesn't have a cause or effect that's generated abroad. Increasingly, we must rely on our allies and foreign governments to share information and data to secure our country.

Until we have a legitimate labor market between Mexico and the United States, people will attempt to come here to work.

Migrants come up and no longer seek to evade the Border Patrol, but are actually left at the border by their smugglers. And they seek out Border Patrol agents or Customs and Border Protection officials to surrender to them and request political asylum. That's the way in which they get entry into a system that will eventually release them into the country.