President Donald Trump vowed to border patrol agents that he would deliver a wall on the southern border, renewing his commitment to border security.

“A real wall, not a little wall … they have them; they don’t work,” Trump said. “You need a real wall that will work 99.9 percent.”

Trump made his remarks during a tour of the Border Patrol National Targeting Center on Friday in Virginia. He spoke to many of the agents and held a roundtable with Homeland Security Secretary Kirstjen Nielsen.

Trump reemphasized his commitment to supporting the agents on the border and the DHS personnel.

“I just want to let you know that the Trump administration is with you folks 100 percent,” he said. “You have not been backed up properly, and everybody knows it. For political reasons, for lots of different reasons. But the Trump administration is with you.”

Nielsen agreed that a wall would be built, but specified that the money requested by his administration would be used to provide more border technology and agents.

“We’re going to build you one,” she said, referring to the wall funding request of $25 billion. “We have a very specific and targeted way in which we will use that money to build a border wall system. Just not just that infrastructure, but the technology and personnel that go with it.”

Nielsen even brought graphics to the briefing, showing Trump how border walls work.

“We’ve seen it, we have evidence, we know that they work,” she said.

Trump again cited the four principals of his immigration reform framework, which includes securing the border, closing loopholes, ending chain migration, and canceling the visa lottery.

ICE Acting Director Thomas Homan, who was also at the briefing, thanked Trump for visiting the facility and empowering his agents.

“For the American heroes sitting behind you, we thank you for letting us do our job,” he said.

He informed the president that since he took office, border crossings were at a 45-year low.

“That just shows you that when we’re allowed to enforce law, we’re going to have an impact,” he said.

Trump said lightly that it was a “great number” but that he was still “very unhappy” about it.

“That’s impressive nevertheless,” he said, as the agents laughed. “But you’ll do much better, good luck.”