By Ted Hesson

WASHINGTON A smuggler with ties to a foreign extremist group helped Uzbek migrants enter the U.S. from Mexico, the White House said on Tuesday, raising questions about a potential security threat.

The smuggler was based in Turkey and had links to the jihadist Islamic State, also known as ISIS, according to a U.S. official who spoke on condition of anonymity. CNN first reported the incident.

Record numbers of migrants have crossed the U.S.-Mexico border illegally since President Joe Biden, a Democrat, took office in 2021, including many from distant nations.

Republicans say Biden encouraged crossings by reversing tougher policies of former President Donald Trump, a Republican. The Biden administration argues that it has instituted more humane policies as migration has challenged countries across the Western Hemisphere.

Of the nearly 2 million migrants encountered at the U.S.-Mexico border between October 2022 and July 2023, 216 were on U.S. watchlists for potential links to terrorism, according to U.S. government statistics.

U.S. intelligence officials discovered a smuggling network to bring Uzbeks into the country and a smuggler with ties to a U.S.-designated foreign terrorist organization, White House National Security Council spokesperson Adrienne Watson said in a statement.

U.S. authorities have no indication that migrants aided by the smuggling network were tied to extremist groups or plotting terrorist attacks, Watson said.

Watson did not confirm links to the Islamic State specifically or that the smuggler was based in Turkey.

Migrants who "fit the profile" of those assisted by the smugglers are being placed in rapid deportation proceedings and "thoroughly vetted," Watson said.

The U.S. official said the FBI is trying to locate about 15 of roughly 120 Uzbek migrants who entered the U.S. through legal border crossings via the network.

An FBI spokesperson said the agency "has not identified a specific terrorism plot associated with foreign nationals who recently entered the United States at the southern border," and declined to comment on specifics.

U.S. Customs and Border Protection encountered some 3,200 Uzbeks at U.S borders in fiscal year 2022, up from fewer than 700 a year earlier.

(Reporting by Ted Hesson in Washington; Additional reporting by Humeyra Pamuk in Washington; Mica Rosenberg in New York, and Lizbeth Diaz in Mexico City; Editing by Mary Milliken and Andy Sullivan)