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.

In the last two years, the Mexicans have detained nearly 400,000 migrants whose intent was to come to the United States. The Mexicans return the detained Central American migrants by bus or by air to the countries they come from.

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.

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.

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.

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.

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