Indeed, many of the illegal crossers who have entered the country in the last two years after being detained have actually been either unaccompanied minors or families who request political asylum. The ability of the smugglers to attract large numbers of families and unaccompanied minors is a function of the inability of our immigration court system to process asylum claims in a timely fashion.

I think there's no question that the barriers, the fences and in certain urban areas, the walls, have had an important effect in terms of increasing the manageability and the security of the border. But in fact as Secretary of Homeland Security General John Kelly acknowledged at his confirmation hearing, walls and barriers alone are insufficient to insure security.

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.

Our security in a global world must be looked at on a continental basis.

Walls and barriers alone are insufficient to insure security.

We can't defend the country by looking at the borderline as the first line of defense rather than as the last line of defense. We have to secure the flow of goods and people by engaging with foreign entities. We assure our security by securing the flows as early as we can before they arrive and as far away from our borders as we can.

If you build a 50-foot wall, you'll soon be confronted with a 51-foot ladder.