Earlier this month, President Trump placed Kevin McAleenan in charge of the Department of Homeland Security. The president fired his previous DHS chief, Kirstjen Nielsen, because he said he wanted to go in a tougher direction. As the new acting secretary, McAleenan is facing the largest wave of illegal crossings at the U.S.-Mexico border in a decade. 100,000 migrants were detained just last month. So we went to McAllen, Texas, one of the busiest sections on the border, to see for ourselves. We were surprised how many families were crossing, where they were detained and how quickly they were released. We asked Secretary McAleenan how he plans to manage the crisis and navigate what may be the most difficult job in Washington.

Sharyn Alfonsi: How do you keep happy-- a boss, who wants to go in a tougher direction, when it comes to immigration, but also work with a Congress that has absolutely no incentive to get anything done in this area before the election?



Kevin McAleenan: Well, first, I believe you can be tough and compassionate at the same time. I'm gonna do what I've always done –give good law enforcement operational, and policy advice to lawmakers and to policy makers. And that's my intent. I think the ground has shifted in this discussion over the past month.

Sharyn Alfonsi: How so?

Kevin McAleenan: I think the numbers from March, I think more members from Congress coming down and seeing what we are facing at the border. They're realizing that something different is happening with this crisis. It's not manufactured it's real. And we've gotta sit down at a table and talk about ways to solve it.

Acting DHS Secretary Keven McAleenan with correspondent Sharyn Alfonsi

Acting DHS Secretary Kevin McAleenan says migrants are crossing the border in record numbers because they know they will be released in the U.S.

Kevin McAleenan: If you come now, and if you come as a family or as an unaccompanied child, you will be allowed to stay. You will be released. Because our court system is so backlogged, and our laws prevent effective repatriation, even if there's no right to stay in the U.S.--

Sharyn Alfonsi: They know, if they come--

Kevin McAleenan: --even if you don't have a valid asylum claim.

Sharyn Alfonsi: --they're gonna be led out the backdoor.

Kevin McAleenan: That's exactly right. And smugglers are advertising that directly in their hometowns.

There is no shortage of people fleeing poverty and crime who want to take the often dangerous trip. We rode with the U.S. Border Patrol deep in Southeast Texas. We saw family after family walking into the U.S. Agent Marcelino Medina asks the migrants if they're okay and points them to where they can turn themselves in to other agents. Further along this dusty stretch of road, he spots a family hiding in the bushes. He asks them if they're okay too, and points the way to where they need to go. Watch their faces when he tells them they are in the United States.



Sharyn Alfonsi: He didn't know where he was, did he?



Agent Marcelino Medina: No. He-- he asked-- how far to the U.S., right? So we were letting him know he's already here. So that's kind of what brought him to tears. He just-- he said he just wanted help.



Last month, a record number of families crossed the border, 53,000 people. Most with only what they could carry. The groups we saw all had children. This woman, eight months pregnant, told us she fled violence in Honduras. She'd been traveling for 15 days.



Sharyn Alfonsi:: You're trying to get her a ride?



Agent Marcelino Medina: I wanted to get her a ride, yeah, but she's-- they're gonna have to walk it.



There are no border agents available to help her. This 277-mile stretch along the Rio Grande River separates the U.S. from Mexico and is one of the busiest sections for illegal crossings. Agents told us they are overwhelmed caring for so many families.

Sharyn Alfonsi: Is this a typical day?



Agent Marcelino Medina: Definitely. You're talking about a sector where recently we've been seeing over 1,000 people a day, and this McAllen Station, the mc-- you can see there's some more coming down that way right now.



Sharyn Alfonsi: It never ends.

Agent Marcelino Medina: You know, it doesn't.

Agent Medina takes us into the brush to show us why so many families cross at this particular area of the border.

Sharyn Alfonsi: So once they get here, they're in U.S. territory. This is U.S. territory right here, and that there--



Agent Marcelino Medina: Correct, this is the-- that's the Mexican riverbank, this is the U.S. riverbank.



In some spots, it takes less than 15 minutes for a smuggler to paddle an inflatable raft full of migrants across. Typically they pay between $3,000 and $9,000 a person.



Agent Marcelino Medina: You gotta keep in mind that all these bo-- everybody that comes across, no matter adult, child, they're paying thousands of dollars.

Sharyn Alfonsi: Is it the cartel running this?



Agent Marcelino Medina: It's-- this-- this is exactly what-- what it is. This is one of their ways they can make money.



We watched as hundreds of migrants walked from the river bank, about three miles, to a levee to turn themselves into Border Patrol. It is orderly and oddly quiet, except for the sounds of the wind and babies crying.





Sharyn Alfonsi: Tell me about your trip here.



Julio Cesar: Muy deficil.



Very difficult, Julio Cesar told us about his 1,600-mile trip from Honduras. Failed crops and threats of violence led him to escape with his daughter. He said his daughter has some sort of chest infection. He hopes he can get her help. As we were talking, his name was called to get on the bus.

This is the beginning of their immigration process. Because they've reached U.S. soil, they are legally allowed to apply for asylum and most will. But first, they are taken to the McAllen Border Patrol Station to be processed. We were allowed to film inside, a first for the facility. They wanted us to see how busy they are. It looked like any other jail except that there were mothers with children peering back at us through the glass. Men are kept separately. Background checks are run and fingerprints are taken. Court dates are scheduled.



Sharyn Alfonsi: How many people-- would you say are in here right now?



Agent Rudy Karisch: How many people would you say?



MALE VOICE: We have 551 subjects here.



Agent Rudy Karisch: Five hundred--



Chief Patrol Agent Rudy Karisch says they are struggling to care for the increasing numbers of families.

Sharyn Alfonsi: What are the agents having to do to deal with this new population that's coming across?



Agent Rudy Karisch: Forty percent of my workforce right now is dedicated to the processing, to the care and feeding, to the hospital watch. So that takes that 40 percent away from their border security mission.



Sharyn Alfonsi: I mean, they're making--



Agent Rudy Karisch: But it is--



Sharyn Alfonsi: --they're making formula. They are bringing juice.



Agent Rudy Karisch: --but it is a strain.



Sharyn Alfonsi: Well there's a pile a diapers right there.



Agent Rudy Karisch: Yeah. And-- that's what we have to do.



The flood of families comes nearly a year after the White House ended its "zero tolerance" policy that led to the separation of thousands of children from their parents. Kevin McAleenan was responsible for enforcing that policy as the head of Customs and Border Protection.

Sharyn Alfonsi: Did you have any regrets about the way that was carried out?



Kevin McAleenan: Yeah. I-- I-- I think-- when you lose the public trust in a law enforcement initiative, and you have to c-- recalibrate at the presidential level-- that means that wasn't successful.

Sharyn Alfonsi: Looking back on it, did it work?

Kevin McAleenan: So the-- the enforcement of the law against parents who violated our border laws and brought children with them-- was effective. But it didn't work in the sense that we lost the public trust in the implementation of that initiative. And I agreed with the president's decision to stop it.



President Trump has said he is "not looking" to restart family separations. But he has threatened to completely shut down the border.

President Trump Soundbite: In many cases, they put their worst people in the caravan, they're not gonna put their best in.

According to the DHS, since October, less than one percent of the migrants who crossed the border had any criminal history. The families we saw were travelling from Honduras, El Salvador and Guatemala, an area of Central America referred to as the northern triangle.

Sharyn Alfonsi: Why so many people from this northern triangle of countries?

Kevin McAleenan: Right. There's poverty. There's drought that's affected the crop yields. Certainly, there are issues with food insecurity. In other parts of Central America, there are still violence issues and gang-control issues.

President Trump Soundbite: We stopped payment to Honduras, to Guatemala and to El Salvador. We were paying them tremendous amounts of money.

An estimated $700 million in aid a year aimed at preventing violence and curbing extreme poverty and hunger in those countries.



Sharyn Alfonsi: He said, "We're not paying them anymore, because they haven't done a thing for us." You've testified in Congress, "We need to continue to support those areas." Do you still believe that?



Kevin McAleenan: So I think the president's right, that we need to have aid that has targeted impact. It needs to support American interests. It needs to support economic development. And it needs to help reduce the causes of migration—everything from insecurity on the food side, to security, in terms of the cities and gang issues.



Sharyn Alfonsi: But wouldn't it just push more people to the border, if there's no aid coming in?



Kevin McAleenan: Well-- aid that's not being used effectively-- by an accountable partner isn't helping.

Sister Norma Pimental: We must address the root causes of why these families are coming. I don't think that if they had given a choice, they would come.

Sister Norma Pimental runs the Catholic Charities Respite Center in McAllen. The Border Patrol has no where to take the families after they are released from custody. Luckily, Sister Norma welcomes them all. They are free to go wherever they like but most stay here for a few days. They are exhausted from weeks of travel and hungry. Volunteers hand out donated clothes and meals.



Sharyn Alfonsi: How many meals are you doing a day in here?



Sister Norma Pimental: Well, thousands of meals. Because we may have, like, 300, 400, sometimes up to 600, you know, people we feeding on that day.



Sister Norma took Secretary McAleenan through the respite center. It is noisy and crowded, with more people wanting to come in. Sister Norma says she doesn't turn anyone away.



Sharyn Alfonsi: If you weren't here, where would all these people go?



Sister Norma Pimental: They would be in the streets, begging and asking for help and-- and exposed to so many people taking advantage of them. You know, it's-- it's so sad that people are suffering like they are.

From Sister Norma's, the families go to the bus station. For some, it was just three days ago they crossed the border. They tell us they are headed to places where they have family or cities where they offer free legal help. Catholic charities gives the migrants signs that say, "Please help me. I don't speak english. What bus do I need to take?"



Sharyn Alfonsi: We saw the migrants leaving Catholic Charities, getting on a bus-- and going off to different parts of the United States.

Kevin McAleenan: Those families are-- are given a court hearing. They're-- they're given a date for a court hearing. And that court hearing could be two years out, five years out, for an initial hearing. That's how overloaded the s-- the system is at this point.

Sharyn Alfonsi: I think a lot of people are gonna be surprised to see that, to see--

Kevin McAleenan: I agree.

Sharyn Alfonsi: -- them get to the bus station. And I think there's that moment when they leave. And you're either gonna think, "That's great," or, "This is horrifying."

Kevin McAleenan: Yeah. The reality of the system today is r-- is very hard to understand.

There is a border wall in McAllen. But it's not on the river. At some points, it is miles inland from where we saw the migrants come ashore. Secretary McAleenan says it does slow down drug traffickers and the migrants who are trying to evade capture.

Kevin McAleenan: We don't need it everywhere but we need it in several key places. And the support we're getting to build the additional wall is essential.

Secretary McAleenan is also lobbying Congress to change the law so DHS can detain families while they await a decision on their asylum claims.

Kevin McAleenan: We've asked Congress to modify that law, to allow us to detain families together, through a fair, transparent and expeditious court proceeding. And if they have an asylum claim or a valid right to stay, under our laws they would receive that certainty. And if not, they would be repatriated to their home country.

Keeping families longer would require more facilities. Potentially costing billions of dollars.



Sharyn Alfonsi: What about tent cities? Is that on the table?



Kevin McAleenan: Tent cities, I think, is-- is a misnomer. For-- for us, right now, we are looking at DHS, at putting up some soft-sided facilities. In fact--



Sharyn Alfonsi: Isn't that a tent? (LAUGH)



Kevin McAleenan: It-- it is-- sure, it could be-- it could be a tent. But I wanna explain the purpose for it. We just had a bipartisan r-- report, from the Homeland Security Advisory Council, that looked at the situation we're facing on the border, and said, "You need additional facilities. You need to be able to take families and children out of a border patrol station," which is a police station. It's built for single adults, who have violated laws. And you need 'em in a better setting.



One day after our interview, we learned DHS had already broken ground on two tent cities in Texas to hold migrants for short-term processing. But concerns linger about whether the Department of Homeland Security should be in the business of holding families in any setting. Last year, despite efforts to treat them, two children died in DHS custody.



Sharyn Alfonsi: Are you worried that another child's gonna die in custody?



Kevin McAleenan: So what I know is our agents and officers are doing everything they possibly can to take care of vulnerable people in our custody. When you're looking at people arriving, sometimes, more than 4,000 in a day, so with that level of volume, with children that young-- with-- with the weather getting hotter, I'm very concerned we could have another tragedy.

Sharyn Alfonsi: Is it a humanitarian crisis? Or is it a national-security crisis?



Kevin McAleenan: It's absolutely both.

Produced by Oriana Zill de Granados and Michael Rey. Associate producer, Emily Gordon.