The man in charge of America’s interior immigration enforcement has a simple message for critics who contend that President Donald Trump’s signature campaign promise is a waste of money: Walls work.

Acting Immigration and Customs Enforcement Director Thomas Homan, Trump’s choice to head the agency permanently, said Thursday on “The Laura Ingraham Show” that physical barriers are effective at stopping people from crossing the border.

“Everyplace they’ve built the wall, it has worked,” he said. “So why would we not want the wall? What price do you put on national security and public safety?”

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Homan said he started his career with the U.S. Border Patrol and was in San Diego when agents were arresting thousands of illegal immigrants a year.

At one time, the 66-mile section of the border extending east of the Pacific Ocean was the most popular entry point for illegal immigrants from Mexico.

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The government in 1993 completed the first 14 miles of fencing. The 10-foot-high fence was made from surplus Army steel landing mat used to make landing strips during the Vietnam War. Later, the United States added a secondary fence behind the first barrier. The two-piece barrier angles toward the south to make it more difficult to scale.

“You tell me. Is that a violation of the statute? And if it is, hold them accountable.”

The flow of illegal migrants apprehended plummeted from 202,173 at the Border Patrol’s Imperial Beach Station in San Diego in fiscal year 1992 — to just 9,122 in fiscal year 2004.

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Homan said there is no reason walls would not be just as effective elsewhere.

The most important issue ICE faces right now is resistance from “sanctuary cities,” Homan said. He said the most extreme of those polices may violate the federal alien smuggling statute, which makes it a crime to harbor or shield illegal immigrants.

“What I have asked the Department of Justice to do is look at these sanctuary city policies — some are worse than others — but are they violating that statute?” he said.

He added, “You tell me. Is that a violation of the statute? And if it is, hold them accountable.”

Homan said he stands by comments he made this week pledging to increase resources in California, where a sanctuary law took effect statewide this week. He said he was not making a threat; it was a promise.

He said he has to beef up staffing because arresting illegal immigrants in the community is harder and more dangerous than taking them into custody from local jails. Not only that, Homan said, but it also puts other illegal immigrants at risk of apprehension.

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“If I can’t arrest a bad guy in the safety and security of the county jail, I will have to go arrest him at a home or a place of employment,” he said. “When I do that, we’re going to find other illegal aliens there, most likely, that weren’t even on our radar. And we’re going to arrest them. So what they’ve done in these sanctuary city policies is they’ve put the immigrant community at greater risk of being arrested by ICE agents.”

Homan said he has a hard time blaming foreigners for wanting to be part of the world’s greatest nation. But when they do so by flouting U.S. laws — America cannot tolerate it.

“You can’t have it both ways — at least not anymore,” he said.

PoliZette senior writer Brendan Kirby can be reached at [email protected]. Follow him on Twitter.