In introducing a third season of the series “Border Wars” set along the embattled U.S./Mexico line,  Michael Cascio, a senior vice president at the National Geographic Channel, overseeing documentary series, said the show chronicles the units that “battle to intercept illegal entrants, fight terrorism, and stop drug smugglers.”

But how big is the job there stopping suspected terrorists at the border (most of the show now is about drug and gun cartels)?

On the panel Cascio presented for “Border Wars,” Justin De La Torre, Acting Assistant Chief Patrol Agent of the San Diego Sector Border Patrol, said “the Federal Bureau of Investigation has the lead on terrorism investigation. However, our primary mission and goal for customs and border protection is to protect the American people by preventing any dangerous people or any dangerous things from entering the United States, whether it be at the port of entry or in between the port of entry.”

But Sylvia Longmire, author of “Cartel: The Coming Invasion of Mexico’s Drug Wars,” scheduled for release in September, was more blunt.

“There is no evidence that [the Department of Homeland Security] has that any operational members of Al Qaeda, Hezbollah, or whatever have used the border to come in, or are actively using the border to come in.”

The third season of “Border Wars” starts Sept. 4 on the National Geographic Channel.