Terrorist attacks are a serious threat that the government needs to try to prevent, but there’s only one problem with Trump’s tweet: A U.S.-Mexico border wall will not prevent terrorism.

Trump is the latest American politician to argue that there’s a large threat from terrorists crossing the Mexican border. In the aftermath of the 2017 Las Vegas shooting, Rep. Scott Perry (R‐​Pa.) claimed that there was “credible information regarding potential terrorist infiltration through the southern border regarding this incident,” even though no such evidence ever came to light. Back in 2014, Rep. Duncan Hunter (R‐​Calif.) said that “ISIS is coming across the southern border.”

There is almost no evidence of a terrorist threat from the Mexican border. Not a single Mexican or Central American has committed or planned to commit an attack on U.S. soil since 1975.

The Center for Immigration Studies has done more than any group to exaggerate the terrorist threat along the border. Yet even its own report could not identify a single individual who has committed or tried to commit an attack on U.S. soil after crossing the border.

According to a CIS report, “15 suspected terrorists have been apprehended at the U.S.-Mexico border, or en route, since 2001.” But only one of the supposed 15 terrorists, Mahmoud Kourani, was convicted — of conspiracy to send money to Hezbollah. Kourani’s offense is serious, but it’s not comparable to murdering people in an attack as Chérif Chekatt did.

Many of the other supposed terrorists on CIS’ list are unidentified, and thus unverifiable. They were stopped by Central American governments and never charged with terrorist offenses, or traveled through the United States to Canada, in the case of Abdulahi Sharif. CIS had to include unidentified people with “credibly suspected or confirmed terrorism ties” to gin up as many as fifteen.

It’s possible that a Muslim terrorist could cross the Mexican border, but we need compelling evidence of a serious threat to take it seriously.

Here are the facts.

Since 1975, only nine terrorists who entered illegally committed or attempted to commit an attack on U.S. soil — and only three of them entered illegally along the Mexican border: Shain Duka, Britan Duka, and Eljvir Duka from Macedonia. They crossed as children with their parents in 1984 and were part of an FBI‐​foiled plot in 2007.

The other six illegal immigrant terrorists came in other ways, some through Canada, and did so in the 1990s or earlier.

A border wall is the anti‐​terrorist version of the Alaska bridge to nowhere. It’s big, expensive, and a waste of resources. All of the people murdered by foreign‐​born terrorists on U.S. soil since 1975 have been killed by those who entered legally. Even if a border wall somehow kept all illegal immigrants out of the U.S., that would not have reduced the terrorist threat over the last several decades.

The terrorist threat in France is very different from that in the United States. From 2002 through December 12, 2018, the annual chance of a person being killed in a terrorist attack in France was about 1 in 4 million. In the United States, the annual chance of a person being killed in a terrorist attack was about 1 in 29.6 million — that’s more than seven times safer than in France.

The terrorists in France in recent years have not crossed a border illegally, but have mainly been French‐​born Muslim youth. They have no jobs, long criminal records, and are largely unassimilated into French culture.

Trump is desperate to fund his wall. It was his biggest campaign promise and crucial to maintain his base’s support. In pursuit of funding for his wall, Trump first argued that illegal immigrants are criminals, but the facts contradicted him. Then Trump argued that the wall would pay for itself, which has been rightly laughed off.

Now he’s using the most far‐​fetched argument of all: The wall will protect us from terrorists and the recent French attack proves it.