The Trump administration’s argument that a border wall is needed to stop terrorists has been strained from the start. President Trump has repeatedly claimed that terrorists were flooding the border (despite the State Department saying there’s no evidence of even one crossing). Vice President Pence falsely claimed that 10 known or suspected terrorists were apprehended every day at the southern border (when in fact that number was for all ports of entry, and is overwhelmingly about airports). Secretary of State Mike Pompeo appeared on Sean Hannity’s Fox News show last week and declined to correct Hannity when Hannity repeated Trump’s baseless talking point.

Whatever legitimate concern there might be about terrorists entering the United States across a porous border, it has been distorted beyond recognition.

Enter Homeland Security Secretary Kirstjen Nielsen to try to salvage the talking point.

In a brief tweetstorm and accompanying “MYTH/FACT” sheet Monday night, Nielsen argued that this is a very real issue. But her argument was full of logical holes, and the fact sheet appears to have been hastily assembled.

Let’s walk through it.

First off, it’s worth noting the context. Nielsen was responding to an NBC News report that found, in the first half of 2018, just six foreigners detained at the border had names on a list of known or suspected terrorists. It’s worth noting that this list is broad, and most people who are detained are not the actual known or suspected terrorists. For example, 35 U.S. citizens were also stopped at the border because their names matched the list.

Now to Nielsen’s tweets.

Again, the terrorist watch list doesn’t mean these are terrorists. It means their names were similar to those of people on the list. The most infamous example of this list’s problems was when Sen. Edward Kennedy (D-Mass.) was repeatedly stopped because his name was similar to an alias that a person on the list used.

And to get a sense of how broad the list is, consider this: The number of terrorist-watch-listed people detained on the northern border in the same period was actually more than six times as many — 41 — per NBC. As Matthew Miller argued, if we need a wall to stop terrorists at the southern border, then we almost definitely need one at the northern border first.

In this tweet, Nielsen declined to confirm any numbers and instead said the number has “increased.” That could be from three, to five, to six, to eight. She also says the number is “sensitive,” which is odd since the administration has gleefully passed along numbers about known or suspected terrorists stopped at all ports of entry — and even put them forward as if they were at the southern border. Why share the gross number, but not break it down for specific areas? And if this number was so sensitive, why were they all sharing it without concern for its accuracy?

If any of these people was actually a terrorist, you can bet that we would know by now. As of July 2017, the State Department said clearly that there was “no credible information that any member of a terrorist group has traveled through Mexico to gain access to the United States.” In September 2018, it updated the phrasing: “At year’s end there was no credible evidence indicating that international terrorist groups have established bases in Mexico, worked with Mexican drug cartels, or sent operatives via Mexico into the United States. The U.S. southern border remains vulnerable to potential terrorist transit, although terrorist groups likely seek other means of trying to enter the United States.”

This is completely true; it’s also a red herring. When it comes to preventing terrorism, resources are finite, and you need to prioritize. You could completely stop terrorists from entering the country by militarizing the border, building walls, and stopping all in-migration and out-migration. But all of those things come at a cost.

The question here is whether the cost of building the wall and all the things that go along with it are worth stopping six people on the terrorist watch list in a six-month period. It seems possible that the estimated $25 billion price tag for the wall might be better spent shoring up our effort to stop terrorists at airports, which is where the vast, vast majority of watch-listed people are stopped — thousands every year. And as noted above, you could even logically argue that it would be better to build the wall on the northern border. You could stop 41 instead of six!

One terrorist is too many, but the numbers matter when weighing one method against others. If the threat is bigger elsewhere, and the money can be better utilized in other ways, that would seem a better alternative. And the State Department’s own words say "terrorist groups likely seek other means of trying to enter the United States.”

Yet again, a Trump administration official used this number without noting that the vast, vast majority of the thousands are at airports.

Apparently it’s okay to release the number of “special-interest aliens” at the southern border and the number of known or suspected terrorists at all ports of entry, but not to combine the two and give the number of known or suspected terrorists at the southern border?

Also, “special-interest alien” is an even broader classification (much broader, in fact) than being on the terrorist watch list; it basically means your travel patterns raise a red flag. As the libertarian Cato Institute has noted, being in any country that has produced a terrorist can raise this red flag. DHS argues that its methods are more refined than that, but it’s clear the definition is very broad — as it perhaps should be when preventing terrorism.

This fact sheet restates some of the points Nielsen makes. But curiously, although it generally employs the personal pronoun “we,” it uses “I” at one point — while basically making a point that Nielsen made in one of her tweets.

Again, it’s worth being concerned about the threat that terrorists who might cross the southern border pose; it’s also worth accurately characterizing it. The Trump administration started by badly misstating the size of the threat, and now when confronted with numbers that suggest little threat, it has decided it is going to be cagey and just ask everyone to trust it.