Department of Homeland Security officials are aware of more than 400 illegal immigrants who were smuggled into the United States at the southern border by an ISIS-affiliated network — most of whom remain at large in the country, according to a new report.

Federal law enforcement is internally tracking and arresting migrants who were released into the U.S. after being encountered at the U.S.-Mexico border. To date, 150 of the 400 have been found and arrested in communities nationwide, but the whereabouts of 50 others are unknown, according to NBC News.

The report would seem to validate the national security concerns some Republican politicians have expressed in the three years since the number of migrants coming across the southern border spiked.

“We know for a fact that dangerous cartels and gangs have used our broken borders as a means to enter the United States. Now, we have confirmation that terrorist-related networks are using similar tactics to smuggle people into our country,” Rep. Tony Gonzales (R-TX) said in a statement Wednesday morning. “Every light is blinking red. We cannot continue to put border security on the back burner—that goes for both the Biden administration and Congress.”

Republicans blame President Joe Biden reversing all of the Trump administration’s immigration policies upon assuming office, though the president has since tacked to the right on the border.

The remaining 200 migrants known to be smuggled by the ISIS-linked network are being monitored and could soon be arrested. They are believed to have been brought into the country from Central Asia and elsewhere.

DHS Secretary Alejandro Mayorkas defended the department in an interview on MSNBC Wednesday morning.

“With respect to the people from Central Asia, we have no evidence that they are individuals plotting to harm the United States. That is inaccurate. It’s very important to note that the safety and security of the American people are our highest priority,” Mayorkas said. “We are proceeding with extreme caution here in the service of the security and safety of the American people, No. 1.”

Earlier this month, the New York Post reported that eight illegal immigrants from the Central Asian country Tajikistan had been let into the country only for federal authorities to track them down months later over their suspected connection to the Islamic State group.

A senior administration official who spoke with NBC News said that the government did not have any information that indicated any of the approximately 400 illegal immigrants had direct ties to the Islamic State group and that the decision to arrest was a precautionary measure.

“In this case, it was the information that suggested a potential tie to ISIS because of some of the individuals involved in [smuggling migrants to the border] that led us to want to take extra care,” a senior Biden administration official said. “Out of an abundance of caution make sure that we exercised our authority in the most expansive and appropriate way to mitigate risk because of this potential connection being made.” 

The U.S. Border Patrol caught more than 172 known or suspected terrorists illegally entering the U.S. from Mexico or Canada in fiscal 2023, which ended last September.

The figure is a jump from single-digit terrorist watch list numbers seen throughout the Trump administration.

CLICK HERE TO READ MORE FROM THE WASHINGTON EXAMINER

Border Patrol can only screen and vet illegal immigrants in custody based on information available at the time.

The U.S. screens immigrants against information in U.S. criminal databases and cannot access criminal records for countries overseas that do not share it, making it impossible to know an individual’s history in certain countries, including Cuba, Russia, Venezuela, and Nicaragua.