CIA director John Brennan
CIA director John BrennanReuters

CIA Director John Brennan said on Wednesday that the terrorist attack on the Ataturk Airport in Istanbul, in which 41 people were killed and hundreds more were wounded, bore the grim hallmarks of the Islamic State (ISIS) jihadist group.

Speaking to Yahoo News, Brennan warned that the fanatically violent Islamic terrorist group wants to conduct similar large-scale attacks in the United States.

Hours after the attack, Turkish media reported that ISIS was responsible, but a Turkish official said it was too early to confirm any links. Turkey's Prime Minister later said that all indications were that ISIS was indeed responsible.

“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 told Yahoo News, using the Arabic name for ISIS.

He credited effective homeland security measures and intelligence for the fact that ISIS has been unable to attack America directly but said he believes the group will keep trying to penetrate American defenses.

“You look at what happened in the Turkish airport, these were suicide vests. 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,” he told Yahoo News.

“I’d be surprised if Daesh is not trying to carry out that kind of attack in the United States,” added Brennan.

Without confirming that the airport bombings were carried out by ISIS, which as of Wednesday morning had not claimed responsibility, Brennan indicated that the method of attack — suicide bombers wearing explosives-laden vests — pointed to the Islamic extremist group rather than to Kurdish nationalists, who have been waging a campaign of violence against the Turkish state.

“It was a suicide bombing [which] is usually more a Daesh technique,” Brennan said, noting that ISIS has a motive to spread its terror to Turkey, which has been targeting ISIS terrorists across the border in Syria.

“Turkey has been cracking down on some of the transit of foreign fighters who are flowing into, as well as out of, Turkey, and they are part of part of the coalition providing support, allowing their territory to be used by coalition aircraft, so there are a lot of reasons why Daesh would want to strike back,” said Brennan.

In the interview, Brennan was blunt about the slow nature of progress both in the fight against ISIS and efforts to push Syrian President Bashar Al-Assad out of power. He echoed somewhat pessimistic comments he made earlier this month before the Senate Intelligence Committee about the enduring strength of ISIS as a terrorist organization with global reach.

“We’ve yet to really thwart Daesh’s ability to reach beyond the Syria-Iraqi borders and put in place some of the plans and preparations to carry out attacks,” Brennan said, adding, “I am very concerned we have not had the success against Daesh in that environment as we’ve had in the core areas of Syria and Iraq.”