Are terrorists slipping across the US border? What the evidence shows.
In recent months, a string of national security figures has warned Congress there is a heightened threat of a terrorist attack on U.S. soil.
鈥淟ooking back over my career in law enforcement, I鈥檇 be hard-pressed to think of a time when so many different threats to our public safety and national security were so elevated all at once,鈥� FBI Director Christopher Wray this spring. Part of that, he said, is an elevated threat of foreign terrorist organizations attacking the United States following the Hamas cross-border raid on Israel Oct. 7. 鈥淥bviously, their ability to exploit any point of entry, including our southwest border, is a source of concern,鈥� he in December.
Former President Donald Trump and Republican members聽of Congress argue that on President Joe Biden鈥檚 watch, the border crisis has become a major national security threat facing the U.S. Among other things, they have聽noted a spike聽in migrants from China crossing the southern border illegally since 2021, many of them military-age males.聽
Why We Wrote This
Fighting terrorism requires alerting the public to threats without playing into terrorists鈥� goal of spreading fear in society. We examine claims that the spike in illegal immigration in the U.S. could open the way for a terrorist attack.
Some dismiss such rhetoric as racist and/or politically motivated fearmongering, arguing that terrorists and spies have the resources to try entering the country legally, while the vast majority of unauthorized migrants are driven by a hope of better socioeconomic conditions. 鈥淭hey鈥檙e here to chase the American dream,鈥� says Sam Schultz, a relief worker at the California-Mexico border. 鈥淭hey don鈥檛 want to blow it up.鈥�
But some top Democrats also express concern. Here we look at the evidence.
What evidence is there that terrorists may be crossing the border?
The U.S. Border Patrol is encountering a far higher number of individuals on the terrorist watch list, with the annual total increasing from single digits during the Trump administration to 172 in fiscal year 2023. That鈥檚 not just a result of increased illegal immigration; the proportion of encounters involving someone on that watch list grew more than tenfold, from 0.0007% to 0.008%, according to government . That鈥檚 a tiny fraction of total flows, but experts point out that just a handful of people can carry out significant attacks.
This spring, Mr. Wray Congress of the potential for a 鈥渃oordinated attack鈥� in the U.S., similar to the one that killed 145 people at a Moscow concert hall in March. The Islamic State (ISIS) claimed responsibility for that attack. The U.S. linked it to the Afghan branch of the organization, known as ISIS Khorasan (ISIS-K), which killed 13 U.S. service members and nearly 200 Afghans at the Kabul airport during the U.S. pullout in 2021. Russia identified four suspected assailants, all from Tajikistan.
So when news emerged June 11 that U.S. authorities had who had crossed the southern border over the past year and had potential ISIS ties, it sparked a new round of warnings about a possible terrorist attack in the U.S. The concerns were further amplified with a subsequent that more than 400 migrants,聽some of whom had been deported but others whose whereabouts were still unknown, had been brought into the U.S. by an ISIS-affiliated smuggling network.
Is the threat increasing?
Historically, there is little evidence that unauthorized immigrants carry out attacks. A University of Maryland project on radicalization only 21 of 3,528 offenders as being an 鈥渦ndocumented resident.鈥� A 2019 academic found that a correlation between migration and terrorism in Western Europe was driven in part by right-wing groups aggrieved by the influx.聽
Until recently there was no empirical evidence that foreign terrorist groups were crossing the U.S. border. Now that is shifting, however, amid increased flows and a broader range of nationalities crossing illegally.
鈥淎l Qaeda and their affiliates, ISIS and their affiliates, have all identified this as a vulnerability in the United States鈥� defense,鈥� says Christopher O鈥橪eary, an FBI counterterrorism veteran now serving as senior vice president of global operations with The Soufan Group. 鈥淵ou have massive waves of people coming across; it鈥檚 certainly reasonable to think that you could blend into that.鈥�
Where does terrorism rank among national security concerns?
鈥淭here鈥檚 no issue I鈥檓 watching more carefully,鈥� Democratic Sen. Mark Warner of Virginia, Senate Intelligence Committee chair, on June 18. 鈥淚鈥檓 monitoring it very, very closely.鈥�
Another congressional leader, GOP Rep. Michael McCaul of Texas, says it鈥檚 part of the broader geopolitical context.聽聽
鈥淲hen you project weakness, you get conflict and war,鈥� says Mr. McCaul, who chairs the House Foreign Affairs Committee and previously led the Homeland Security Committee. 鈥淭he last line of defense is the border.鈥�
He points out that when the U.S. abruptly left Bagram Air Base in Afghanistan in 2021, thousands of ISIS-K prisoners were freed. And he鈥檚 concerned that conflicts in Europe, the Middle East, and the Pacific could spiral into another world war.
Part of the challenge is how to allocate U.S. resources. Mr. O鈥橪eary, who worked on FBI counterterrorism investigations for more than two decades until stepping down last fall, says the government has pivoted away from the terrorism threat to focus on Russia, China, and great-power competition. He stresses the need to stay alert, 20-plus years into the global war on terror, with U.S.-designated terrorist groups, such as Al Qaeda and ISIS, growing. For example, Al Qaeda鈥檚 core membership increased approximately tenfold from to , according to estimates.
鈥淲e know what鈥檚 going to happen if we close our eyes and turn away and hope the bogeyman is going to go away,鈥� he says.
What is being done?
According to U.S. Customs and Border Protection, when Border Patrol agents encounter migrants crossing the southwest border illegally, they screen and vet those individuals. Agents ask for names, birthdates, and other biographical information, and take fingerprints and retinal scans. This biometric data can help establish a migrant鈥檚 identity if they use an alias or don鈥檛 have an ID. Their information is then checked against law enforcement and national security databases for 鈥渄erogatory鈥� information.聽
No such information turned up during the initial screenings of the eight Tajiks. If such information comes to light later, as it did in this case, 鈥渆nforcement action鈥� will be taken accordingly, Department of Homeland Security Secretary Alejandro Mayorkas said June 26 in Tucson, Arizona. 鈥淭he safety and security of the American public is indeed our highest priority.鈥�
Reports from the department鈥檚 inspector general, however, identify gaps in screening 鈥� from Customs and Border Protection being biometric data from a Department of Defense watchlist, to not having a dedicated procedure to screen asylum applicants whose cases drag on, to obtaining but not sharing information from the FBI鈥檚 Terrorist Screening Center, which resulted in the of a migrant on the terrorist watch list.聽
Another gap is the inability to screen 鈥済otaways,鈥� hundreds of thousands of whom have been detected crossing by cameras and sensors, or by border agents too occupied to respond.聽
So, what can be done? The president has taken executive action to stem the tide. CBS News that encounters are down to their lowest level since 2021, citing preliminary data.
On the law enforcement front, the Department of Justice in June that a high-ranking leader of MS-13 was arrested on terrorism charges. Less than a week later, the FBI 鈥渢he dismantlement of the largest ISIS online propaganda network and infrastructure鈥� in the world, thanks to coordination with European partners.
A key line of defense is maintaining good ties with communities where potential terrorists may try to blend in, says Daniel Byman, senior fellow with the Warfare, Irregular Threats, and Terrorism Program at the Center for Strategic and International Studies. He notes that Muslim American communities have tipped off law enforcement to many suspected Al Qaeda and ISIS terrorists, including Omar Mateen, who later killed 49 people in the 2016 Pulse nightclub shooting in Orlando, Florida.聽
鈥淪omething to think about with all this,鈥� he says, 鈥渋s when you start to demonize different migrant communities, they tend to be less willing to go to the police.鈥�
Staff writer Francine Kiefer contributed reporting from the border at Jacumba Hot Springs, California.聽
