On Wednesday morning, White House press secretary Sarah Sanders went on Fox News’s morning show, Fox & Friends, to defend herself after claiming on Sunday that “nearly 4,000 known or suspected terrorists come into our country illegally” — a false claim that Fox News Sunday host Chris Wallace shut down immediately.

In an effort to defend her Sunday statements, Sanders made the argument that even one terrorist coming into the United States is a problem worth building a multibillion-dollar border wall over.

“The bottom line is whether it’s one, four, 14 or 4,000, one terrorist coming into our country in illegal fashion to do us harm is one too many,” she said.

FOX & FRIENDS: Sarah, why did you dramatically inflate the number of people on watchlists who were detained by Border Patrol?@PressSec: "The bottom line is whether it's one, 4, 14 or 4,000, one terrorist coming into our country in illegal fashion to do us harm one too many." pic.twitter.com/x3HrdANppq — Aaron Rupar (@atrupar) January 9, 2019

Homeland Security Secretary Kirstjen Nielsen made the same argument on Monday, tweeting that “one terrorist reaching our borders is one too many.”

I am sure all Americans would agree that one terrorist reaching our borders is one too many. These are just the terror suspects we know about who reach our border. — Sec. Kirstjen Nielsen (@SecNielsen) January 8, 2019

This is a very popular argument. It’s even made in other countries. But it is not a particularly good one — and it’s not a particularly conservative one, either.

Conservatives get it on guns. They don’t on the border wall.

To begin with: Yes, terrorism is bad. It is also, fortunately for all of us, extremely rare, particularly in the United States. As Alex Nowrasteh of the Cato Institute wrote in 2018, Americans are far more likely to be killed by an animal than by a terrorist attack: “From 1975 through the end of 2016, 7,548 people have been killed by animals while 3,438 have been killed by all terrorists.” (And yes, that includes the terrorist attacks on September 11, 2001.)

Moreover, the chances of being killed by a foreign-born terrorist are roughly one in 104.2 million per year — meaning that yes, it is possible, but decidedly unlikely, especially when one considers that the chance of being killed by an asteroid while on Earth is somewhere around one in 1.6 million.

Conservatives and libertarians generally understand this about other subjects — on guns and gun control, for example. Conservatives who support gun rights have long recognized that while, as the Federalist’s Sean Davis wrote in 2015, “any amount of violent crime is too much,” gun violence and the deaths they cause have been decreasing rapidly since 1993. That means the threat of guns and gun violence, terrifying as it is, is relatively minimal.

On the possibility of bans on so-called “long guns” and rifles, the National Review editorial board wrote in February 2018: “All long guns combined — from granddad’s duck gun to the scary-looking black instruments that so repulse our progressive friends — represent a vanishingly small share of the weapons used in violent crimes in the United States, something on the order of 2 percent in a typical year. In spite of the media hysteria, violent crimes involving so-called assault rifles are so rare that the FBI data don’t even break them out into a separate category.”

In short, despite recent, awful events like the Parkland shooting, conservative writers and thinkers have made the argument that the hypothetical (and minimal) threat of a rifle being used in a mass shooting isn’t worth curtailing the civil rights of law-abiding gun owning Americans.

Which brings us to the border wall.

Why the border wall represents a new form of “security theater”

A Trumpian border wall, which began largely as a campaign gimmick, would not fix whatever is going wrong on our country’s border with Mexico. (One might also note that Trump had two years to address a wall with the GOP in charge of both the House and Senate.)

As my colleague Dara Lind has written, not only have there been border wall-type construction projects on the southern border since at least the early 1990s, a wall of the type envisioned by Trump and his most dedicated supporters wouldn’t even fix the real crisis that exists at the border: more families with children coming to the border than US officials can handle.

It might be fair to call the current situation at the border a “humanitarian crisis.” But it isn’t why Trump shut down the government. And it isn’t something a wall can fix. The point of walls is to prevent people from crossing into the US undetected. That’s not what most of the families and children who are crossing are doing. They’re turning themselves in to the nearest border agent they see on the US side. Not all of them, but a large share, are seeking asylum — seeking to live legally in the US. That’s something they have a legal right to do even if they crossed illegally — and it’s something they could do at a port of entry even if there were a wall across the entire border. The Trump administration’s specific problem with the influx of asylum seekers isn’t that it isn’t catching them — it’s that it can’t quickly deport them, and can’t detain them for the entire time until they are deported, because of extra legal protections for asylum seekers as well as for children and families. (The administration calls these “loopholes” that create a policy of “catch and release.”)

In other words, the problem at the border isn’t terrorists. And the data bears this out. According to NBC News, there were “only six immigrants at ports of entry on the US-Mexico border in the first half of fiscal year 2018 whose names were on a federal government list of known or suspected terrorists.” (And it’s also worth noting that being on a watchlist is not itself a certification of guilt.)

It’s accurate, then, to say that a Trumpian border wall represents not security, or safety, or a worthy expense for American tax dollars, but “security theater.” In a 2009 piece for CNN, Bruce Schneier wrote that security theaters are “security measures that make people feel more secure without doing anything to actually improve their security.”

While actual security can be gained by investigations or analysis, “security theater” is intended to show the public that everything is fine — without actually doing anything to make the public more, well, fine.

The best example of security theater is airport security. As JJ Rich wrote for the Reason Foundation last year, Transportation Security Administration agents patting down children and making us all take off our shoes and belts has less to do with effective security practices and more to do with making us feel secure — in effect, curtailing civil liberties and making flying a more challenging experience purely for our feelings.

Nowrasteh from the Cato Institute, who did that research on terror deaths compared to deaths from animal attacks, told me, “The wall, and immigration enforcement more broadly, is the most expensive form of security theater since the War on Terrorism.”

And he’s not alone. In a piece for Reason, Steve Chapman wrote that the Trumpian border wall — which wouldn’t stop drugs, probably wouldn’t curtail undocumented immigration (which generally takes place via airports, not the border), and would represent a massive outlay of government spending — is a piece of “performance art.” Performance art, mind you, that would curtail the rights of private landowners and represent a tremendous extension of executive power — something conservatives have long railed against.

The “just one terrorist” argument wielded by Sanders and Nielsen is the same argument the TSA has used in the past to defend enhanced boarding procedures on airplanes or the use of body scanners: If just one terror plot is stopped by these invasive and arguably un-Constitutional procedures, it’s worth it.

But conservatives should know better. They should know that terrorism is actually incredibly rare, and a border wall is likely to do little to affect any future terrorist attack or keep terrorists out of the country, especially since terror suspects have generally traveled through the air to get to the United States.

They should know that more people on the Terrorist Screening Database were stopped along the northern border with Canada than along the southern border with Mexico in 2018. They should know that a wall will act merely as security theater to make Americans feel better at their own expense.

And then perhaps they should say so, out loud.