McAleenan said that 538 children in Border Protection's custody who were separated since May have been reunited with their parents.
Melania Trump is heading back toward the southern border of the United States.
This time, she was wearing simple white pants with a thin black track stripe running halfway up the side, a black boat neck top with a 3/4 sleeve (how Audrey Hepburn of her), and black flats.
This is the second border detention facility she has toured this month, she visited a facility in Texas last Thursday where the media became caught up in the jacket she wore while boarding and leaving her flight.
The first lady met with Border Patrol officials soon after landing at Davis-Monthan Air Force Base, where she said she was looking forward to touring the Border Patrol's facility in Tucson. Many were placed hundreds of miles away from one another and have been struggling to be reunited. After federal officials began separating families in May and sending kids to shelters while their parents awaited prosecution, the public reacted with outrage.
The choice spawned a slew of speculation about what the first lady, a former model, may have meant.
"It's a jacket. There was no hidden message", Grisham said at the time. On Thursday she wore a black sweater and white trousers as she boarded a government plane in Washington, with no visible writing on either garment.
First lady Melania Trump was expected to visit immigration centres Thursday housing migrants apprehended at the U.S. -Mexico border. The last time, "she wasn't able to visit a DHS facility, and she wants to learn from the people on the front lines at the border", Stephanie said.
Trump stirred an global furor with a policy called "zero tolerance" that resulted in the government taking immigrant children from parents caught unlawfully crossing the US border with Mexico.
"We're working with Congress, hopefully, to provide more resources and the ability to actually enforce the law", she said.
Later, Sessions defended the President's immigration policy, saying Donald Trump had made it clear to avoid separating families, but the authority "is going to work to prosecute all of those adults who come here unlawfully".
Anticipating a trip to Phoenix, protesters also gathered outside the Southwest Key facility in the city's west side.
Mr Trump last week signed an executive order to halt the separation of families at the border, at least for a few weeks, but the order did not address the reunification of families already separated.