Last Tuesday, President Trump signed an executive order halting the separation of children from their parents arrested for illegally crossing the border. Now families will be detained together until the end of their immigration proceedings. However, the “zero tolerance” immigration policy remains in place. It requires prosecution of all illegal crossings to prevent individuals from trying to enter the United States.

The “zero tolerance” policy is the second major Trump Administration policy designed to limit entry into the United States. The first—a travel ban against seven primarily Muslim majority countries—was introduced shortly after the Administration took office and just upheld by the Supreme Court. Both are broad, sweeping policies that the Administration claims will improve U.S. national security.

Does the “zero tolerance” policy make us more secure from either terrorism or crime? Let’s look at the evidence.

Does “zero tolerance” protect us from terrorism?

Since 9/11, counterterrorism has been the U.S.’s top national security priority. One might assume that a major initiative to prevent entry into the U.S. would have a clear link to counterterrorism. While the “zero tolerance” policy has not been specifically portrayed as a counterterrorism effort, the Administration has frequently pointed to the terrorist threat as a reason for more restrictive immigration policies.

A January report from the Department of Homeland Security and the Department of Justice on international terrorism went so far as to claim that roughly three out of every four (402 out of 549) individuals convicted of international terrorism-related charges in U.S. federal courts between September 11, 2001, and December 31, 2016 were foreign-born.

The report’s methodology drew scrutiny – both for its narrow focus on international terrorism rather than all terrorism in the U.S., and for including approximately 90 individuals who were brought to the United States to stand trial. It also ignored the findings of the Department of Homeland Security’s own analysts that demonstrated that many of the foreign-born terrorists were radicalized well after coming to the U.S. Others criticized the report as mischaracterizing the threat, noting that since 2002, foreign-born terrorists have killed 34 people, while U.S.-born terrorists have killed more than three times that number. A study released by Fordham University Law School’s Center on National Security – which examined only attacks tied to the Islamic State — found that the perpetrators tend to be Americans born in the United States.

What’s more directly relevant to the “zero tolerance” policy is how rarely those who entered the U.S. illegally, let alone from the southern border, have had anything to do with terrorism. In its Country Report on Terrorism, the U.S. State Department even stated that “There are no known international terrorist organizations operating in Mexico… and no credible information that any member of a terrorist group has traveled through Mexico to gain access to the United States.”  Illegally crossing the border is sufficiently dangerous, difficult, and unreliable that terrorist groups have sought other ways to penetrate the U.S.

More generally, Latin America is not a major hub of terrorist activity that threatens the U.S. The most significant designated terrorist organization originating from Latin America is the left-wing Revolutionary Armed Forces of Colombia, better known as the FARC, which is in the midst of a peace process and little threat to the U.S. In addition, the Lebanese Shia group Hezbollah operates in the region primarily as part of its worldwide illicit enterprise to fund its agenda in the Middle East.

Does “zero tolerance” protect the U.S. from crime?

The Trump Administration regularly argues that illegal immigrants from Latin America should be kept out because they bring crime.

However, several studies suggest that illegal immigrants don’t actually increase crime. A major longitudinal study found that illegal immigration did not increase violent crime. In Texas — on the front lines of immigration from Latin America — 6.3 percent of its population is undocumented, but only 4.6 percent of the prison population is – suggesting that illegal immigrants are underrepresented in criminal convictions, compared to their presence in the population.  A Cato Institute study finds that all immigrants, “[e]ven illegal immigrants are less likely to be incarcerated than native-born Americans.”

In promoting the “zero tolerance” policy, Trump and Attorney General Jeff Sessions have argued that they’re stopping organized criminal groups from entering the U.S., especially MS-13, which the FBI characterized as “exceedingly violent.” Of those apprehended by U.S. Border Patrol for gang affiliations in recent years, the majority come from MS-13.

But it’s not clear that the “zero tolerance” policy will damage MS-13. ICE was already undertaking an aggressive campaign against the group, so aggressive that it drew criticism. Border Patrol has apprehended 275 individuals with MS-13 affiliations so far in 2018, and 228 last year. That’s unlikely to hurt an organization that the FBI estimates has between 6,000 and 10,000 members in the U.S. In fact, MS-13 actually began in the United States in the 1980s and was exported to Central America through deportations, where it has flourished.

What’s more, the number of individuals with gang affiliations apprehended by Border Patrol actually dropped by nearly half from 2014 to 2017. Of all the illegal immigrants that the Border Patrol apprehended in those years, less than 1 percent were affiliated with gangs. A significant number were instead seeking to enter the U.S. to escape violence at home — from the very organized criminal groups the U.S. wants to keep out.

National security implications

Both terrorist organizations and organized criminal groups do threaten U.S. national security. The Trump Administration has used broad, sweeping policies on immigration and travel in an effort to keep those threats out.

But those threats do not solely — or perhaps even primarily — come from outside U.S. borders.

Moreover, the zero tolerance policy requires tremendous financial and human resources, resources that cannot then be used elsewhere. It is far from clear that this major investment will commensurately diminish national security threats.

Tricia Bacon (@tricbacon) is an assistant professor at American University’s School of Public Affairs, former State Department counterterrorism analyst, and author of Why Terrorist Groups Form International Alliances (University of Pennsylvania Press, 2018).