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.

Most people who live at the border or are familiar with the border know that a Berlin-like wall stretching from San Diego to Brownsville is not necessary. And the costs would be prohibitive. And there are places on the border, such as the Arizona desert or the open terrain around the Big Bend in South Texas, where Mother Nature has created her own barrier that is not easily passable. Or if you do pass through it, you are easily detected.

The law change during the Bush administration gave the Department of Health and Human Services a central role in relocating Central American minors in the United States.

We need to realize that the economic situation between Mexico and the United States is not just one in which we trade with one another. We make things together. We have shared production platforms. Cross-border trade is part of a single production process, and while apparently the Trump administration will seek to re-examine elements of that production platform, it is what it is and won't be easily dismantled.

The work the Mexicans are doing in terms of migration control on Mexico's southern border is crucial to our own border 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.