CIA director: Attack at Istanbul airport has hallmarks of Islamic State, could happen in U.S.

The attack Tuesday night at an international airport in Istanbul reeks of the work of the Islamic State terror group and could happen here in the United States, CIA Director John Brennan said in an interview Wednesday.

The agency official told Yahoo! News in fact that the shooting and bombings at Ataturk Airport that left 41 dead should serve as a warning to the United States.

"I am worried from the standpoint of an intelligence professional who looks at the capabilities of Daesh … and their determination to kill as many as people as possible and to carry out attacks abroad," Brennan said, using a term that is an acronym for Islamic State in Arabic. "I’d be surprised if Daesh is not trying to carry out that kind of attack in the United States."

No one has yet stepped forward to take responsibility for the attack, which erupted after three men stepped out of a taxi at the international terminal, gunfire erupted and at least one blew himself up, officials said.

Brennan told Yahoo! News during an interview at CIA headquarters that he believes Islamic State, also known as ISIL or ISIS, will eventually try to penetrate American borders. The suspects who carried out fatal shootings in Orlando and in San Bernardino, Calif., were considered by authorities to be Islamic State sympathizers.

In the attack in Turkey, the alleged perpetrators showed a sense of determination, the CIA director said.

"You look at what happened in the Turkish airport, these were suicide vests," Brennan said. "It’s not that difficult to actually construct and fabricate a suicide vest … so if you have a determined enemy and individuals who are not concerned about escape, that they are going into it with a sense that they are going to die, that really does complicate your strategy in terms of preventing attacks."

Vests outfitted with explosives tend to be a tactic employed by Islamic State, he warned.

The U.S. strategy to weaken Isis is to push Syrian President Bashar Assad out of power, Brennan said, but he conceded that Assad is getting stronger rather than weaker in terms of influence.

“Relative to where he was on the battlefield last year, (Assad) is in a better and stronger position," Brennan told Yahoo! News.