Newly introduced legal changes would be a significant step in addressing the “core aspect” of the immigration crisis at the southern border, Acting Secretary of the Department of Homeland Security Kevin McAleenan said Wednesday.

Appearing on “America’s Newsroom,” McAleenan made the case that after implementing the policies and repatriating those without “meritorious” claims, “we’re going to see a reduction in that flow significantly at the border.”

“It’s a key aspect of our multilayered strategy,” he told anchors Sandra Smith and Jon Scott.

The new legislation was unveiled in a press release and news conference Wednesday morning. The administration is moving to end a federal agreement that limits how long migrant children can be held in detention. They would also establish family residential facilities that he described as “campus-like” with educational, medical, and dining centers. A court fight is expected to follow.

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On the release, President Trump is quoted as saying: “To protect these children from abuse, and stop this illegal flow, we must close these loopholes. This is an urgent humanitarian necessity.”

“Through July we saw 475,000 family units. That’s more than three times any previous full year arriving at our border in just ten months,” McAleenan said. “And, they’ve been coming to exploit a vulnerability in our immigration framework that says if you have a child with you, you cannot be held for more than 20 days.”

McAleenan argued that the current immigration system is incentivizing. He pointed to a recent conversation with a Guatemalan father who “basically said everybody knows that bringing a child is a passport for migration and release into the U.S. This helps us change that dynamic.”

He also cited the influx of migrants from 2014 to 2015 -- 68,000 migrants according to McAleenan -- in the “first family crisis” under the Obama administration: “When the initial decision was made to detain families through their proceedings by the Department of Homeland Security at that time…the message went out.”

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“Families knew that they couldn’t just cross the border and be released and the numbers dropped 90 percent overnight. We do expect a very similar deterrent effect when we can demonstrate that integrity in the system and actually get immigration results,” he stated.

McAleenan also pushed back on almost immediate negative criticism from 2020 Democratic presidential candidate Julián Castro, who tweeted: “Separating migrant children from their parents is appalling—but indefinitely detaining families isn’t a better alternative.”

“He’s criticizing what the prior Democratic administration did to help establish the integrity of the administration system and address what was then an unchecked flow,” he told Smith and Scott.

The president told a gaggle of reporters at the White House on Wednesday afternoon: “President Obama had separation; I'm the one that brought [families] together.”

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“The incentives that our system has provided for families and criminal organizations to profit off of them is a much worse situation than completing an immigration proceeding in a fair and appropriate setting,” McAleenan said.