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WATCH: Homeland Security head McAleenan questioned over treatment of migrants

WASHINGTON (AP) — A top Trump administration official said Thursday the number of family separations at the border has fallen since last summer’s zero tolerance policy, and they are done only for compelling reasons.

McAleenan is scheduled to testify before the House Oversight committee at 10 a.m. ET. Watch live in the video player above.

Acting Homeland Security Secretary Kevin McAleenan said fewer than 1,000 children have been separated from families out of more than 450,000 family groups that have crossed the border since October. He said they are separated because of health and safety concerns, among other reasons.

“The vast majority” of families are kept together, he said.

That tally does not include children who come with older siblings, or aunts and uncles and grandparents and are separated under longstanding policy meant to guard against human trafficking. McAleenan said Congress would need to amend laws to allow border officers more discretion in order to keep those groups together.

McAleenan was speaking Thursday before the House Oversight Committee investigating border problems. His testimony comes amid a growing outcry over the treatment of migrants at the border, an internal investigation into Border Patrol agents who posted crude and mocking posts in a secret Facebook group and the move this week to effectively end asylum on the U.S.-Mexico border.

Lawmakers mostly questioned McAleenan about the policy that led to the separation of more than 2,700 children from parents last year. A watchdog reporter later found thousands more may have been separated. Democrats and Republicans on the committee also traded barbs over emergency border funding and the moment the massive numbers of border crossings became a crisis.

“As I have testified and warned publicly, dozens of times this year and last, we are facing an unprecedented crisis at the border,” McAleenan told the committee.

U.S. Customs and Border Protection officials have encountered more than 800,000 migrants crossing the border from Mexico. Over 450,000 were families.

“Combined, that means over 300,000 children have entered our custody since October 1st,” he said.

Oversight Committee Chairman Elijah Cummings, a Maryland Democrat, said McAleenan was an architect of the family separations. McAleenan wrongly called reports of filthy, overcrowded border facilities “unsubstantiated,” Cummings said.

“The administration wants to blame Democrats for this crisis, but it is the Trump administration’s own policies that are causing these problems,” Cummings said.

Lawmakers didn’t question McAleenan on the new asylum rules before they recessed for a vote. But the new policy is by far the biggest change to how the U.S. handles immigrants. Under the new rules, anyone who comes to the U.S.-Mexico border through another country would not be eligible for asylum. They could affect tens of thousands of people who cross the border each month. There are thousands more on waiting lists at ports of entry who will now likely be denied asylum.

The new rules rules come into play during an initial asylum screening that happens after a migrant is first encountered by Border Patrol, so they won’t make an immediate dent in overcrowding at border facilities. The rules also must survive a legal challenge.

The number of border crossings dropped last month amid hot weather and a crackdown by Mexico on migrants to its southern border.

McAleenan said facilities are less crowded, especially for children who are only supposed to be held in border holding stations for 72 hours. Delays along the entire immigration system have forced migrants to wait in crowded border facilities not meant to hold people for more than a few days.

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