As the U.S. southern border becomes an increasing issue for voters, Sen. Marco Rubio, R-Fla., on Sunday warned that ISIS-K terrorists could try to exploit the border to launch an attack on Americans like the deadly attack that the group has claimed to have carried out in Moscow on Friday.

Rubio, the vice chair of the Senate Intelligence Committee, said during an appearance on ABC's "This Week" that Americans "should be very concerned" about the potential threat of ISIS-K after FBI Director Christopher Wray confirmed to him that the terror group has its own human trafficking network.

"I think common sense tells you, if they run a trafficking network of people, that would most certainly use it to move operatives into the United States," Rubio said. "So I'm not claiming there's an imminent threat to the U.S., but I am saying that border situation and the existence of that network is a threat to the United States."

"If they could do what they did in Moscow, in the United States, they would do it in a heartbeat," Rubio added. "They want to do it."

WAHT IS ISSI-K, THE TERRORIST GROUP TIED TO MOSCOW CONCERT HALL ATTACK AND 2021 ABBEY GATE BOMBING?

More than 130 people were killed and at least 154 others were injured at a concert hall in suburban Moscow on Friday. Russian authorities said they have apprehended 11 suspects in connection with the attack.

The Islamic State group, aka ISIS, claimed responsibility for the deadly attack in a statement on its affiliated social media channels. The intelligence community said it believes the ISIS affiliate in Afghanistan called Islamic State Khorasan, or "ISIS-K" as it is known, carried out the attack, a U.S. official told Fox News.

DEATH TOLL RISES TO 133 IN MOSCOW TERROR ATTACK, 11 SUSPECTS ARRESTED

ISIS-K is the same terrorist group that killed 13 American service members at Abbey Gate during the hasty U.S. withdrawal from Afghanistan in 2021. 

Rubio said that since the U.S. withdrawal from Afghanistan, the terror group can now operate openly despite opposition from the Taliban, which he says doesn’t "have the capability" to take them on.

Rubio also says that ISIS-K’s aspirations go beyond infiltrating Iran and Russia.

"They would love to do what they did in Moscow, here inside the United States," the senator said. "And it's something we have to be very vigilant about when we have a border in which 9 million people have come across in the last three years."