U.S. intelligence intensifying focus on possibility that ISIS members try to enter through southern border

U.S. intelligence and security officials are increasing their focus on the country's southern border following the arrest earlier this month of eight men from Tajikistan with possible ties to the Islamic State group, also known as IS or ISIS, a Voice of America report said.

According to the outlet, authorities are concerned that the constant flow of illegal migrants crossing the southern border with Mexico has attracted the attention of the terrorist group as a strategy to enter the U.S.

While the initial background checks of the eight arrested men came up clean, U.S. law enforcement subsequently turned up information indicating potential ties to the Islamic State, as per the article.

All of the men arrived in the U.S. through the southern border in the past year.

"It's not lost on us that the people who killed over 150 Russians in that theater were from the same part of the world," said Ken Wainstein, the U.S. Department of Homeland Security's undersecretary for intelligence and analysis, in reference to the March attack on a Moscow concert hall claimed by the ISIS' Afghan affiliate.

Testifying before the House Homeland Security Subcommittee on Counterterrorism on Wednesday, Wainstein said concerns about the potential for IS to exploit the border have prompted daily meetings with the director of the U.S. National Counterterrorism Center (NCTC) and unprecedented cooperation with the FBI.

But he tried to downplay concerns stemming from intelligence suggesting that the ISIS-linked human smuggling network may have brought more than 400 migrants from Central Asia across the southern border into the U.S.

"There is no information which suggests those particular individuals are terrorist operatives," Wainstein told lawmakers.

Information on the 400 migrants, first reported by NBC News based on three U.S. officials whose identities have been withheld, indicates that more than 150 of the migrants have been apprehended.

So there is still no official confirmation of these 400 migrants or the ties of these 8 arrested men to ISIS, but the information is being read by many as a shift in the counterterrorism landscape, as U.S. officials have for decades denied that terror groups were using the border with Mexico to enter the country.

As for the eight men from Tajikistan, Homeland Security Secretary Alejandro Mayorkas told reporters in Tucson, Arizona, Wednesday that, "They are in removal proceedings as we speak."