Originally Published: 29 AUG 23 07:00 ET

Updated: 30 AUG 23 07:23 ET

By Katie Bo Lillis, Evan Perez, Priscilla Alvarez and Natasha Bertrand, CNN

(CNN) — The FBI is investigating more than a dozen migrants from Uzbekistan and other countries allowed into the US after they sought asylum at the southern border with Mexico earlier this year, a scramble set off when US intelligence officials found that the migrants traveled with the help of a smuggler with ties to ISIS, according to multiple US officials.

While the FBI says no specific ISIS plot has been identified, officials are still working to “identify and assess” all of the individuals who gained entry to the United States, according to a statement from National Security Council spokesman Adrienne Watson. And they are closely scrutinizing a number of the migrants as possible criminal threats, according to two US officials.

Though there is no evidence at this point to justify detaining anyone, the episode was so alarming that an urgent classified intelligence report was circulated to President Joe Biden’s top Cabinet officials in their morning briefing book. For some counterterrorism officials, it shows that the US is deeply vulnerable to the possibility that terrorists could sneak across the southern border by hiding amid the surge of migrants entering the country in search of asylum.

The incident kicked off a flurry of urgent meetings among top national security and administration officials at a time when Republicans have hammered Biden on the security of the southern border heading into the 2024 campaign. Staff on key congressional committees have been informed of the incident, according to two sources familiar with the matter.

Earlier this year, a cohort of migrants from Uzbekistan requested asylum and were screened by the Department of Homeland Security, part of a rising number of asylum seekers who have traveled to the US from Central Asia in recent years. There was no information in any of the intelligence community’s databases that raised any red flags and the people were all released into the US pending a court date. 

It was only later, when the FBI learned about the existence of a human smuggling network helping foreign nationals travel to the US – and that this network included at least one individual with connections to ISIS – that national security officials put the pieces together.

FBI agents around the country immediately rushed to try to locate the migrants and investigate their backgrounds. The bureau also worked with Turkish authorities, who arrested the smuggler and other members of his network at the behest of the US, and has subsequently obtained information from him to aid its investigation, US officials said. 

“There was no indication—and remains no indication—that any of the individuals facilitated by this network have a connection to a foreign terrorist organization or are engaged in plotting a terrorist attack in the United States,” Watson said in a statement to CNN.

Since the intelligence became available, homeland security officials also began detaining, vetting and, ultimately, expediting the removal of other migrants encountered at the southern border who “fit the profile associated with individuals who were facilitated by this network,” Watson said.

The ISIS-linked smuggler is not believed to be a member of the terror group, but more like an independent contractor who has personal sympathies with the organization, according to US officials. The intelligence community now believes it is unlikely that he was assisting these individuals at the behest of ISIS. Most are believed to be seeking a better life in the United States. 

For some Biden administration officials, the episode is an example of the system working as it should: intelligence came to light about a particular group of migrants and the US responded with an investigation determining that they did not pose a threat.

“While the FBI has not identified a specific terrorism plot associated with foreign nationals who recently entered the United States at the southern border, we always work with our field offices across the country, as well as our domestic and international partners, to identify any potential illegal activity or terrorism threats,” the FBI said in a statement to CNN.

But the US has not yet located all of the individuals who traveled as part of the network, according to Watson’s statement. And more than 15 of the migrants tracked down are still under scrutiny by the FBI as possible criminal threats, according to one US official.

Some law enforcement and intelligence officials privately expressed concerns that an unusual increase in the number of migrants from Central Asia, a region that isn’t known to be a major source of refugees, didn’t spark more investigation by US border authorities.

“We continually assess our security architecture to ensure that we are best poised to respond to threats to the homeland,” Watson said in her statement to CNN. “Moreover, we will continue to constantly recalibrate our screening, vetting, and processing of those encountered entering the United States to ensure that we are taking into account the most up-to-date information at our disposal and with an unyielding commitment to protecting Americans and the homeland from the full range of potential threats.”

Watson also said in her statement that the US is working with foreign partners to shut down travel routes associated with the smuggling network.  

In a statement to CNN, an official from the Turkish Embassy in Washington said that Turkey had arrested four members of a smuggling ring that, the official said, the US had told Turkey aided the travel of Uzbeks, Russians, Chechens and Georgians residing in Turkey to the United States.

The Turkish official denied that there was a connection between any of the four arrested individuals and ISIS.

A senior administration official suggested that Turkey did not have access to the same intelligence as the US about the smuggler’s links to ISIS.

“Working with partners, the US can’t always share the full scope of the information picture. We appreciate Turkey’s cooperation,” the official said.

A DHS spokesperson told CNN that the department along with its “counterterrorism, and law enforcement partners screen and vet individuals prior to their entry to the United States to prevent anyone known to pose a threat from entering the country. DHS continually monitors all available sources of intelligence and information related to potential threats and if any new information emerges, we work closely with the FBI and other partners to take appropriate action.”

Terrorism and the border

The episode sits squarely at the nexus of two of the thorniest and most politically fraught security challenges facing the Biden administration: terrorism and the border. Biden has grappled with how to prevent terror attacks on the US homeland at a time when the intelligence community and the military have shifted many of their resources away from counterterrorism in favor of threats from China and Russia. 

Administration officials have also grappled with limited resources as they face a growing number of migrants at the US southern border. Migration patterns to the United States have changed dramatically in recent years, with people arriving to the United States from more than 150 countries – the result, officials say, of unprecedented mass migration around the world. 

In July, border authorities encountered more than 183,000 migrants at the US southern border, according to US Customs and Border Protection data. 

Both the Biden and Trump administrations have been forced to wrestle with similar cases of suspected terrorists trying to enter the country at the southern border. 

But the number of individuals encountered at the border with records in the terror watchlist in a given year is extremely small and represents a very small percentage of the total number of known or suspected terrorists who try to enter or travel to the US through other means.

When USCBP officers process migrants at the border, they take biometrics, like fingerprints and facial scans, and run individuals through certain law enforcement databases for any red flags.

Migrants arriving at the US southern border from central Asia may trigger additional screening because of the distance and cost required to take the journey, according to a former senior DHS official, which raises questions about why an individual from that part of the world would choose to cross at the US southern border.

But if there is no so-called derogatory information about a person in US databases, then the migrant is released pending a court date. Although some asylum seekers do not appear for their court date, officials say that US law enforcement has surveillance tools at its disposal to locate those individuals in the United States. 

It’s not clear whether this particular group of migrants received secondary screening at the time, but it’s possible – even likely –  that they did. But because officials believe the Turkish smuggler was acting as a run-of-the-mill human smuggler, not an agent of ISIS, it’s not clear that they would have been detained or in any other way handled differently even if the government had known about his role at the time they were processed. 

For some intelligence and law enforcement officials who spoke privately to CNN, that’s part of the problem. The US government has to figure out how to define who is and who isn’t a threat in a murky world where criminal activity like human smuggling is often commingled with amorphous connections to terrorism organizations. It is particularly difficult to disentangle those threads for desperate migrants fleeing countries where terror groups routinely recruit and operate.  

Speaking at a July congressional hearing, FBI Director Christopher Wray said, “From the FBI’s perspective, that we are seeing all sorts of very serious, very serious, criminal threats that come from across the border.”

Wray said the southern border was becoming “more of a priority” for the FBI.

Some intelligence officials who viewed the intelligence report sent around earlier this month worry that ISIS may shift its tactics to target the southern border, long a bogeyman on the political right but one that intelligence officials say has yet to become a reality.

For other officials, the intelligence reporting to top policymakers was better described as an appropriately cautious response by a responsible government – a warning describing the theoretical risk to the United States so that national security agencies could understand the threat and determine how best to harden American defenses. 

“Whenever we have indicators that criminal actors – such as those involved in human smuggling – have connections to terrorism, we work diligently with our partners to investigate and understand how foreign terrorist organizations may attempt to exploit their capabilities so that we can best mitigate any risk to the American public,” the FBI said in its statement.  

This story has been updated with additional reporting.