Acting Homeland Security Secretary Kevin McAleenan said Tuesday that his department needed more troops on the southern border, where he expected to leverage a "robust partnership" with the Department of Defense and continue making rapid progress on a barrier blocking unauthorized entry.

He was responding to Fox News host Dana Perino on "The Daily Briefing" when she asked how he planned, without additional funding from Congress, to give voters the sense that the administration was making progress building the border wall that the president had made a central part of his 2016 campaign.

"We're going to show a lot of progress this year," he told Perino, noting that wall construction had already outpaced the progress seen in federal projects of similar size. "We've already built the FY17 funding in less than two years. That shows how aggressively we're moving out on this."

He also pointed to support from the Department of Defense, which he said has been "critically engaged" in border security and freed up the border patrol to focus on primary law enforcement duties.

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Earlier in the day, Trump tweeted that the wall was "being rapidly built." "The Wall is being rapidly built! The Economy is GREAT! Our Country is Respected again!" he said.

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For much of the president's first term, he and congressional Democrats repeatedly clashed over the border wall. When the two sides couldn't agree on the issue at the end of 2018, the government shut down and only re-opened alongside Trump's decision to declare a national emergency in order to expedite wall funding.

Trump has taken a multi-faceted approach to immigration policy and faced legal challenges to many of his decisions. On Tuesday, the Supreme Court heard oral arguments on his administration's decision to ask about citizenship on the 2020 Census — a move Democrats blasted as illegal.

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During his interview with Perino, McAleenan reiterated the president's concern about the law surrounding unaccompanied minors and migrant families at the border. He highlighted two particular changes he'd like to see from Congress.

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"The two targeted changes we need the most are the ability to detain families together through a fair and expeditious immigration proceeding," he said.

"And secondly, the ability to have unaccompanied children, who are being enticed into the smuggling cycle from Central America — being able to repatriate them safely in concert with the Central American government," he said.