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CIA Chief: Attack 'Bears the Hallmarks' of ISIS; Obama Vows to 'Do What's Necessary to Protect Our People'; Trump Responds to Istanbul Airport Attack. Aired 5-6p ET

Aired June 29, 2016 - 17:00   ET

THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

JAKE TAPPER, CNN ANCHOR: I now kick you over to Brianna Keilar. She's in for Wolf Blitzer, right next door in THE SITUATION ROOM.

[17:00:10] BRIANNA KEILAR, CNN ANCHOR: Happening now, hallmarks of ISIS. The CIA director says the bloody attack that killed 41 people at Istanbul's airport bears the hallmark of the terror group's depravity. As investigators race to learn how the attackers penetrated high security, there is growing concern that ISIS is scouting its next target.

Heightened alert. The CIA chief warns that ISIS is trying to carry out a similar attack in the United States. Will it keep testing American defenses? The July Fourth holiday bringing new concerns about airport security.

And sleeper cells. Were the Istanbul bombers part of a large cell inside Turkey? How many other terrorists could be out there, ready to strike.

And politics of fear. Donald Trump says terrorists think America is weak. He says the U.S. needs to respond viciously to ISIS's brutality, declaring that even waterboarding is not tough enough. But what did he mean when he says you have to fight fire with fire?

Wolf Blitzer is off today. I'm Brianna Keilar. You're in THE SITUATION ROOM.

ANNOUNCER: This is CNN breaking news.

KEILAR: Our breaking news: as investigators scramble to learn who was behind the bloody airport attack, and how three penetrated tight security, killing 41 people. CIA director John Brennan says the attack bears the hallmarks of ISIS, and he's warning that ISIS is trying to carry out similar attacks inside the United States, adding ominously it is not difficult to build an explosive vest.

As Turkish authorities study images of this massacre, trying to learn how the attackers breached the airport quicker (ph), opened fire and set off their bombs, the airport itself is back to business. Reopened to flights just hours after the attack. But there is growing concern about the threat to this country. And security has been stepped up at major U.S. airports as millions of travelers are setting out for the July Fourth holiday. I will speak with Senator Angus King of the Intelligence Committee who

just had a briefing and will tell us more. And our correspondents, analysts and guests have full coverage of the day's top stories.

Let's go straight to CNN senior international correspondent Nima Elbagir in Istanbul.

What is the latest on the investigation there, Nima?

NIMA ELBAGIR, CNN SENIOR INTERNATIONAL CORRESPONDENT: Well, really, the main thrust of the investigation at the moment, Brianna, the crucial thrust, is who else is out there? Turkish officials tell us that they have begun the identification of the bodies, what's left of the bodies of the attackers.

The blast was so strong that they're really only working with just the lower halves of the bodies, and they're trying desperately to figure out who are these people. At the moment, all they indications, they tell us, are that these were foreign fighters and immediately that opens up a whole -- the possibility of a whole web. Much like in the Brussels attacks, they were delivered to the airport by a taxi driver who has been questioned and released this evening. And we just want to take a look at this.

(BEGIN VIDEOTAPE)

ELBAGIR (voice-over): Tonight, Turkish authorities are pouring through videos and trying to piece together the most lethal attack ever at an airport. Shortly before 10 p.m. Tuesday, three men arrived by taxi at Istanbul Ataturk Airport. Armed with assault rifles and wearing suicide vests, they stormed the international terminal.

UNIDENTIFIED FEMALE: He's shooting up two times, and he beginning -- shot the people.

ELBAGIR: As the attackers make their way inside, videos show terrified passengers and airport workers scrambling for cover.

UNIDENTIFIED FEMALE: We were there hiding, and other people were trying to break the glass, trying to get out of the lounge.

ELBAGIR: Security cameras captured the moment of one blast. And another scene shows one of the terrorists running and falling to the ground, shot by police. He drops his weapon, and then moments later, detonates his explosive vest. According to officials, a third attacker then detonates his suicide bomb in the arrival bay.

UNIDENTIFIED MALE: We heard a huge explosion, and I knew immediately it was a bomb.

ELBAGIR: A horrific scene. Ambulances rushed to treat the wounded and carry the dead. But trying to identify them is difficult, because only the lower half of their bodies were left intact.

No terrorist group has taken responsibility for the attack, but Turkish and U.S. officials say all indications are ISIS was behind the deadly assault.

UNIDENTIFIED MALE: Findings by our security forces indicate this attack was carried out by ISIS.

[17:05:10] ELBAGIR: U.S. officials point to the use of multiple suicide bombers in a coordinated attack that used weapons and explosives and the targeting of a major transportation hub serving international passengers.

Yet not even 24 hours after the horror, the airport was reopened. As workers clear debris and clean the blood-soaked halls of the terminal.

(END VIDEOTAPE)

ELBAGIR: Astonishingly, it was through these doors just behind me, Brianna, that people 24 hours ago were fleeing for their lives. Today you can see they're queueing, trying to get through security and try to return to some semblance of normality -- Brianna.

KEILAR: Nima Elbagir for us at Ataturk Airport, thank you.

President Obama today called Turkey's leader, offering U.S. support to the NATO ally and vowing that the U.S. will do what it must to safeguard its own citizens. The president just met with his Canadian and Mexican counterparts.

CNN White House correspondent Michelle Kosinski is traveling with the president. She's live for us from Ottawa with the latest -- Michelle.

MICHELLE KOSINSKI, CNN WHITE HOUSE CORRESPONDENT: Hey, Brianna.

Twice today we heard President Obama top his remarks in Canada with the Turkey attacks. And it just underscores how many times now in just a short amount of time we've seen President Obama's foreign travel, which he would like to focus on other issues, interrupted by or overshadowed by global terror.

So yes, he talked about the phone call with Turkey's president this morning. Remember, it was only two weeks ago that President Erdogan was calling President Obama and offering his condolences after the Orlando terrorist attack. This time the U.S. offered Turkey any and all assistance that's necessary.

And we're hearing the White House emphasizing today concerns over the fact that ISIS can still launch attacks like this, as well as commitments among countries including Turkey to defeat it. Listen.

(BEGIN VIDEO CLIP)

BARACK OBAMA, PRESIDENT OF THE UNITED STATES: We're still learning all of the facts. But we know that this is part of our broader, shared fight against terrorist networks. And we will continue to work closely with Turkey to root them out.

Meanwhile, we're going to do what's necessary to protect our people. I'm confident that we can and we will defeat those who offer only death and destruction. And we will always remember, even as there are those that are trying to divide us, that we are stronger when we come together and work toward a better world together.

(END VIDEO CLIP)

KOSINSKI: The White House today also talked about how he's been trying to prioritize working with Turkey on better closing its border with Syria. That's something that has been a problem for a very long time. There's still about 60 miles in which ISIS fighters can go back and forth.

Today the White House acknowledged that there is more that can be done -- Brianna.

KEILAR: Michelle Kosinski traveling with the president in Canada, thank you.

CIA Director John Brennan says the Istanbul attack bears the hallmarks of ISIS, and he's warning that ISIS may try a similar attack here inside the U.S. CNN justice correspondent Pamela Brown is here, and this is, I think, what a lot of people have been wondering, and he is raising this concern.

PAMELA BROWN, CNN JUSTICE CORRESPONDENT: Yes. And it is troubling to think the CIA chief has been warning about these kinds of attacks. He says the U.S. is not immune. Now, even though no terrorist group has claimed responsibility, the suspicion, as we've been hearing, falls on ISIS. And as ISIS loses some of its territory in Iraq and Syria, intelligence officials say expect the group and sympathizers of it to carry out more attacks just like the one in Turkey against the west.

I spoke to one official who called it "the new normal." Here's what CIA chief John Brennan had to say about the risks to the U.S.

(BEGIN VIDEO CLIP)

JOHN BRENNAN, CIA DIRECTOR: The United States, as you well know, is leading the coalition to try to destroy as much of this poison as possible. So it would be a surprise to me that ISIL is not trying to hit us, both in the region as well as in our homeland.

If anybody here believes that the U.S. homeland is hermetically sealed, and that the -- DAISH or ISIL would not consider that, I think I would guard against that.

(END VIDEO CLIP)

BROWN: U.S. officials say while there are a number of soft targets in the U.S., it is harder for terrorists to acquire the materials necessary to make suicide vests as the ones used in Turkey. And it is much harder for foreign fighters to make it back into the U.S. than it is in Europe. And the Homeland Security Department says there are no known credible threats, but officials are urging Americans to be especially vigilant as we approach the Fourth of July holiday weekend and the final week of the holy month of Ramadan -- Brian.

KEILAR: All right, Pamela. Thank you so much.

Joining me now is a key member of both the Intelligence and Armed Services Committees, Independent Senator Angus King of Maine.

And sir, I know that you are fresh out of a briefing. What can you tell us?

[17:10:08] SEN. ANGUS KING (I), MAINE: Well, I can't really tell you anything that was classified. But basically, the information is as you have been reporting it.

There is no confirmation yet that this is ISIS, although it certainly looks like it. The odd piece of evidence, though, is that they haven't claimed credit. Usually, if they pull off something like this, they immediately want to claim credit, because in their weird world, that helps them to recruit. So that's a bit of a caution about coming to the firm conclusion that it was them.

On the other hand, the head of Turkey, the president of Turkey, has said it was ISIS. If it was the PKK that Turkey has a lot of problems with, he probably would have said that immediately. So it looks like ISIS, although I think we just -- as the president said, we have to wait till we have all of the facts.

KEILAR: You've been talking to top intelligence officials. Can you tell us anything more about the attackers? Was this just limited to these three? Do we think that this might have been part of a wider network?

KING: Well, it's really hard to say. I mean, this is so similar to what happened in Brussels. There is a likelihood that there are other people that are involved there in Turkey.

One of the questions is there's sort of a hierarchy, if you will: is it directed by or inspired by? Are these people foreign fighters? Are they ISIS fighters that crossed the border into Turkey? Or are they people that are living in Turkey and were inspired on the Internet or some other way by ISIS's ideology.

It's really impossible to tell that now. I know that that's one of the immediate concerns of the Turkish officials, as it would be for us. I mean, it's one of the first things we looked at after Orlando, was is this guy connected with other people? Is it a cell? And right now, we just don't have the facts on the ground in Istanbul.

KEILAR: CIA Director John Brennan raising concern today. He said, quote, "I'd be surprised if DAISH/ISIS is not trying to carry out that kind of attack in the United States." Do you agree with that assessment?

KING: Well, I don't know about the United States, but I know generally. I mean, here's what's happening. They're being squeezed very seriously in their so-called caliphate in Syria and Iraq. They've lost something like 25 or 30 percent of the ground that they held this time this year.

We just took the forces, Iraqi security forces, just took Fallujah. There's going to be greater pressure on Mosul and now Iraq and Syria.

As that happens, as they get squeezed down, the thinking is that they're going to lash out in Brussels, or Paris, or Turkey, or -- I hope not, but possibly someplace in the United States to keep their -- their reputation alive as a powerful and vital force. And we've got to show that they aren't winning. They aren't winning on the ground, certainly in and Syria.

And I think one of the things that was important today is that the Turks did not mess around. They went right back to business in that airport the next day, and they're not letting these guys win over there. Will it happen here? Nobody can guarantee that it won't. But I think it's much less likely, much harder for them to pull off something like that here than in some of these other countries.

KEILAR: It is a big travel weekend ahead of us here in the U.S., ahead of July 4. There are going to be -- there will be so many public gatherings of people. Are there any known threats to the homeland as we head into this weekend?

KING: None. The term that I have heard used is no actionable intelligence; in other words, no direct threats. Now, before this attack, just two or three days ago, the State Department issued a travel warning to Turkey. Now, I don't think it was related to this particular threat, but it was a general travel warning.

Look, we've got to go about our lives. I'm flying tomorrow back up to Maine. And you know, we've just got to get about our lives. Otherwise, if we just drop everything and cower in our houses, these guys have won the war. I'm not going to let them do that.

KEILAR: You mentioned the squeeze that ISIS is feeling on the battlefield, that its lost a quarter or so of its territory, of its caliphate, as it declared it. And we have seen this pattern emerge, that when they do feel the squeeze, there may be a large attack like this. Is there a concern that there could be more?

KING: Absolutely I think that is one of the concerns. And as they get squeezed down on the ground, they will try to lash out in other parts of the world. But we can't let them win there either.

I mean, they're getting sort of desperate, I think. And these attacks, it's hard to say that someone that blows themselves up is cowardly, but to plan an attack that the sole purpose is to kill innocent women, children, and men is the definition of cowardly, it seems to me. And it just makes no sense. I don't know what it's going to accomplish.

In fact, in this case if it turns out to be ISIS, Turkey, who is the closest neighbor to Syria, is going to get much more engaged. And I think ISIS will come to rue the day that they struck the Ataturk airport.

KEILAR: All right, Senator King, stay with me.

Senator King is a member of the Senate Intelligence Committee. He's just out of a briefing with top intelligence officials on these attacks in Istanbul. We'll have more after a break.

(COMMERCIAL BREAK)

[17:19:35] KEILAR: Breaking news, the CIA director says the Istanbul airport attack bears the hallmarks of ISIS, and he says ISIS is likely trying to carry out similar attacks in the United States.

We're back now with independent Senator Angus King of Maine. He's a member of both the Intelligence and Armed Services Committees.

And sir, I know you did just come out of a briefing with top intelligence officials. You -- Ash Carter, the defense secretary; the chairman of the joint chiefs of staff; representatives from the State Department; as well as counterterrorism officials.

I know a lot of that is classified; you can't tell us a lot of what you heard there. But just give us a sense of the concern about how vulnerable U.S. airports are into this busy travel weekend.

KING: Well, I think one thing that should be mentioned is that, in the -- in the FAA bill that went through the Congress a month or so ago, we did some significant beefing up of airport perimeter security. There's something called viper teams, which usually involve dogs, explosive-sniffing dogs. They're trying to protect the perimeter of airports. So we're working on it.

It's impossible -- I mean, this is the dilemma of being a free society, Brianna. We can't -- we don't want police and soldiers shoulder to shoulder in every airport, every ball game and every place that we congregate, every Fourth of July parade. So we're a free country, and that means there are risks.

But the Homeland Security Department, the TSA, and all of the facilities that are working on this are, in fact, on the alert and are paying attention to it. And so will there be a strike? Nobody can guarantee, but we have no evidence that there will be, except for the fact that these guys want to strike us. But so far they've only been able to exercise this kind of control in Europe.

Now, here's the real danger. Here's the nightmare. And that is the guy in Orlando, or the couple at San Bernardino, they were Americans. They lived here; they were located here. They'd never been -- I think he'd been to the Middle East, but by and large, they were radicalized online. They weren't part of a plot. There's no way to intercept communications, because there weren't any communications, except what was in their head. And then they go and buy guns and pull off an attack.

That's the -- that's the danger, and that's what's so worrisome. And by the way, I can't help but say that's why we fought so hard earlier this week to keep people off the no-fly list for buying guns. I just think that's ridiculous. You can't get on an airplane, but you can walk into a gun store and buy an AR-15. But that's another subject.

But yes, it's a risk, but I think, again, we've just got to continue to live our lives. Otherwise, these guys win. KEILAR: All right. Senator Angus King, thank you so much for sharing

that information with us as you come out of this briefing. We appreciate it.

And coming up, we have much more on our breaking news. We will go live to the scene of the bloody airport attack in Istanbul, which the CIA director says it bears the hallmarks of ISIS. You're in THE SITUATION ROOM.

(COMMERCIAL BREAK)

[17:27:02] KEILAR: Breaking news, CIA Director John Brennan is warning Americans that terror groups like ISIS will likely try to carry out attacks similar to the airport bombing in Turkey in the U.S. CNN's Brooke Baldwin is joining us now from the scene of that attack.

Brooke, you just flew in a short time ago to Ataturk Airport. Tell us what that was like.

BROOKE BALDWIN, CNN CORRESPONDENT: Yes, I mean, just like so many Americans, I was on vacation in France, and got the call to say get on a plane and go to Istanbul. And my first takeaway, and I'll walk you through what I saw here in Istanbul Airport, versus even leaving Charles De Gaulle in France this morning, was in France, Paris, I saw more security, more men in uniform carrying assault rivals there than I did having spent two hours, essentially, from landing here in Istanbul and finally hopping outside of the airport so I can be with you live on CNN.

Once you know, you land, and let me just underscore for people home in the United States, you fly into a place like JFK or LAX or Dulles. This is on par, if not larger. And I've covered, sadly, enough mass shootings, terror attacks. There is often, after a mass casualty, a quiet in the air.

And the first thing you notice when you walk into this airport, the hustle and the bustle. The parents, you know, hollering at their kids. The soccer balls being kicked around. There isn't that quiet, that sense of subdued nature that I've experienced. So that was one huge takeaway for me. You walk through the airport, it is jam-packed. It is a hot summer night here in Istanbul. And you just wouldn't know what had happened here a little more than 24 hours ago.

I was in contact with a close friend of ours in Istanbul, and he was on an e-mail chain with the owner of this airport who referred to this as Turkish resilience. I know there's been a lot of criticism as far as how could they open this airport up? You know what happened in Brussels. Think about what happened in so many other places.

And the fact that it's back open, you know, contaminated crime scene, at all. But when you talk to, you know, Turks here, they call it their own resilience. The owner of the airport telling my contact in Istanbul he wants it all fixed. This is a quote, fixed and up and running fully by tomorrow morning.

And Brianna, the only sign as I was walking outside in the hustle and bustle of this warm night, with the taxi drivers, and people yelling "Get out of the way," was the massive shattered glass. The glass from floor to ceiling, the ceiling tiles down, you know, in a position as if, obviously you knew there had been massive explosions nearby. But that was it. That was the only way I knew something absolutely horrendous had happened here -- Brianna.

KEILAR: It's really amazing they just got right back to work, opened things back up and getting things moving at the world's 11th largest airport. Brooke Baldwin, thanks so much for a look there from the scene of the attack.

[17:30:02] I want to get more analysis now from our terrorism experts. We have Soner Chagapday. He's a senior fellow and director of the Turkish research program at the Washington Institute. Also, hometown is Istanbul, bringing a lot of personal knowledge there. CNN senior law enforcement analyst and former FBI assistant director, Tom Fuentes; and CNN national security commentator Mike Rogers. He's also the former chairman of the House Intelligence Committee.

Soner, I think we heard Brooke describing this with, except for the shattered glass and ceiling tiles that had not bee replaced, you almost would not have known that this had happened. Why was it so important to get things moving so quickly?

SONER CHAGAPDAY, SENIOR FELLOW/DIRECTOR OF TURKISH RESEARCH PROGRAM, WASHINGTON INSTITUTE: Yes, in Brussels it took the Belgians weeks to get the airport up and running. I think this was a deliberate effort on behalf of the Turkish government, the Turks, to get a message outside. Because if ISIS, by carrying out the attack, tried to undermine their image as a place that's safe for business and safe for visitors, by getting the airport up and running and functioning in under -- less than a day after the attack, Turkey is basically saying, "Never mind. This was just a lapse. We're back in business."

The idea with the attack was really to hurt Turkey's tourism industry. This brings about $30 billion in revenue. Thirty-five billion people come to Turkey a year. Istanbul is the sixth most visited city in the world. So it would have really hurt the city's image, had the airport remained shut down. It shows a resilience.

And it also shows that the Turks, an historic memory of having had attacks before, going back to the '70s, '80s and '90s. I remember that, as a kid when I was raised in Turkey, of course, airports had similar security as what you would here now, which are common but were unthinkable back then. And I think Turkey has that history. So it's not hard for them to get good security up and going again.

KEILAR: Are there any vulnerabilities created, Tom, by reopening so quickly?

TOM FUENTES, CNN SENIOR LAW ENFORCEMENT ANALYST: Well, not if they have the same security they had before and maybe just a little bit of an increase. They already had, probably, one of the best security systems in the world of any airport, far more than any U.S. airport.

So I think what more could they really do, other than shut the whole city down? And as Soner mentioned, they're not going to do that and correctly so.

KEILAR: You think that this diminishes the effect of, assuming this is ISIS, of the attack -- of terrorists? Does this diminish the impact that clearly they were trying to have on the psyche of people in Turkey, and also people around the world, watching them just get back on their feet so quickly?

MIKE ROGERS, CNN NATIONAL SECURITY COMMENTATOR: Yes, I think it does. It's a psychological game. Terrorism in and of itself is a psychological tool that includes, obviously, horrendous violence. So when they do this and they come right back and the place is crowded and flights are leaving, that is score one for the Turks.

However, it still has an impact. They're already down about a third in tourism in Turkey. This will continue to have an impact. We're going -- I think even the president, Erdogan, today was talking about being more aggressive in the fight against terrorism. This is that opportunity to actually, I think, start dealing with the problem that is in places like Raqqah, Syria.

KEILAR: How will that manifest itself, Turkey becoming tougher on that?

ROGERS: Well, you know, Turkey has had an interesting game -- they've played an interesting game in this so far. So they were against Assad. They've attacked some Turkish -- or excuse me, some Kurdish positions in Syria early on. And I think finally it's all meeting itself out here, that Turkey is going to have to be an active player in helping us, the United States and other NATO allies in actually putting -- putting some folks in places like Raqqah, Syria. That is where their command energy is. That's where they recruit, they train, they propagandize. And that is exactly where we're going to have to hit them.

I think Turkey can play an important role in that. And I think an attack like this, this is their eighth suicide attack this year. We'll, I hope, get them interested in finally doing something more aggressive.

KEILAR: All right, you guys. Stand by. We have more ahead with our wonderful panel here. We'll be back after a quick break. Coming up, the latest on our breaking news. We'll have a closer look at a new tactic being used by terror groups.

(COMMERCIAL BREAK)

[18:38:44] KEILAR: Breaking news: investigators in Turkey are trying to figure out how three terrorists bypassed security and killed 41 people at Istanbul's Ataturk Airport.

Our Brian Todd has a closer look at the evolving tactics of terror groups like ISIS. What are you learning, Brian?

BRIAN TODD, CNN CORRESPONDENT: Brianna, tonight we're learning a lot more about a tactic we likely saw in Istanbul, one we also saw in Paris, where the terrorists don't rely just on a suicide bomb. In fact, it's automatic weapons fire at the initial points of assault which does the most damage.

(BEGIN VIDEOTAPE)

TODD (voice-over): The terrorist falls. Then, in one horrifying flash, appears to detonate himself. Turkish officials say he and his team shot their way into the terminal, likely using a terror tactic that's been seen frequently in recent attacks, a tactic that has its own name, inghimasi.

MICHAEL WEISS, CO-AUTHOR, "ISIS: INSIDE THE ARMY OF TERROR": Inghimasi, their M.O. on the ground in Syria and Iraq is to shoot up at checkpoints. And then they actually, some of them even run up to the enemy and hug them before detonating the bomb to take them out with themselves. So, in a sense, the ultimate kamikaze warrior.

TODD: Inghimasi is variously translated as meaning a willingness to die, to plunge yourself at the enemy, as having no chance of returning alive. Tactically, it often means a terrorist fires his automatic weapon first, detonates his suicide bomb later.

[17:40:02] (on camera): What's the reason for the tactic? To maximize casualties?

JAMES CARAFALO, HERITAGE FOUNDATION: Well, there is an argument that numbers matter. We saw that in Orlando. We saw that in Istanbul. When you take out a bunch of people, that's bigger press. It gets more attention.

ISIS is trying to be strong. They want to be seen as powerful. And so those kind of larger attacks, I think, do achieve the narrative they're looking for.

TODD (voice-over): Though ISIS has not claimed it carried out the Istanbul attack, CNN director John Brennan says the airport assault bears the hallmarks of ISIS. Earlier this month, the terror group's propaganda arm called an attack near Baghdad an inghimasi operation, where ISIS fighters, quote, "assaulted Iraqi forces and clashed with them for hour before detonating their explosive belts."

JOHN BRENNAN, CIA DIRECTOR: They really don't have to worry about an escape route. It makes carrying out that attack so much easier.

TODD: U.S. counterterror and law enforcement officials tell CNN they believe there has been increased discussion among jihadists since the Paris attacks about the lessons terrorists have learned from that assault. Whether it's more effective to fire first with automatic weapons, then detonate suicide bombs when they're cornered. In Paris almost all the casualties were from gunfire.

Terror experts say it makes it even more difficult for western intelligence agencies to disrupt these attacks in very public, open places.

WEISS: There is no way to stop somebody who's just making a mad dash for a window pane, and wants to blow a hole in it and kill loads of people coming in and out of an airport terminal. (END VIDEOTAPE)

TODD: Now underscoring the difficulty that counterterror and intelligence agencies have in getting ahead of this kind of attack is one difficulty the Turkish government is having after the Istanbul attack. A Turkish government source telling CNN the terrorists in Istanbul have not been identified yet, because only the lower parts of their bodies are intact -- Brianna.

KEILAR: And of course, we're hearing, Brian, some new warnings from the very top of the intelligence chain that ISIS could carry out a similar attack inside the U.S. Is this a tactic that could be seen here then?

TODD: Absolutely, Brianna. It's weighing heavily on the minds of homeland security officials tonight. Security perimeters, as we've seen at U.S. airports, are inside terminals. The access to those terminals wide open. So terrorists could use this tactic of spraying gunfire first to maximize casualties, then setting off the bombs. The key, of course, is to disrupt that before it happens. It's an enormous challenge for intelligence agencies like the FBI to do that domestically.

KEILAR: Brian Todd, thank you so much.

Let's get more now from our terrorism experts. We're joined, as well, by senior international correspondent Clarissa Ward. And it was you, Clarissa, who brought this up yesterday, as soon as we saw this happen, and we were wondering who may be responsible for this. Inghimasi, this is a hallmark of ISIS.

CLARISSA WARD, CNN SENIOR INTERNATIONAL CORRESPONDENT: Yes, it is. It's not actually just ISIS. It's other sort of Islamist militant jihadist groups that use them, as well.

But essentially, what they are are kind of the special forces of ISIS in a sense. Because they're highly trained warriors. And the idea, as you just heard from Brian, is that they, you know, try to do as much damage as they can, try to have as many casualties before ultimately detonating their explosive vests.

And the word in Arabic actually comes from the root meaning "to plunge deeply." And the idea is to plunge deeply into the heart of the enemy. The understanding being, of course, that you're not coming back from that.

So they're incredibly dangerous. They're very well-trained. They're heavily armed, and they are very, very, very rarely captured alive, Brianna.

KEILAR: Chairman Rogers, does this show an adaptability on the part of ISIS and other terrorist organizations?

ROGERS: Absolutely. So they're learning through a whole host of ways. A, guarantee that these aren't the only three people that were involved in this plot. Somebody built that vest; somebody assembled the weapons, likely, for them. Of course, probably some assistance in surveillance. So there are other people engaged.

Those people, those are the ones that are doing the research. They're trying to figure out OK, the suitcase bombing in Brussels didn't work as well. So if you notice, they went back to suicide vests. It's higher, the explosive, unfortunately, has more of a lethality when it comes to civilians.

So that, I think, is exactly what they're doing. They're using social media. They're using their own operational interests and intelligence, and they're applying it to new techniques.

KEILAR: If you're looking, Tom, at getting some assistance to these three suicide bombers, how many more people would you think would be involved? Many more?

ROGERS: I would guess probably at least half a dozen. Normally, the people that have the expertise to make suicide vests don't put one on themselves. They need to keep the expertise for other people to sacrifice themselves. Same thing with the people that supply the guns, that do the logistics, do the background and the surveillance.

So they have a coordinated effort, and then they take the lowest ranking people in that group and say, "Do that." And then they go sacrifice themselves. So -- but the particular techniques of this, you know, we've seen similar attacks like this over the years, with firearms and explosives.

[17:45:00] In the Mumbai attack, in that case they didn't have suicide vests but they had grenades. So the 10 guys have initiated that attack and held a city of 20 million hostage for a weekend, were doing it with automatic rifles and hand grenades. So it doesn't have to just be a suicide vest, but it could be a, you know, multifaceted attack with multiple types of weapons.

KEILAR: Real quick, Soner. This may provide some incentive for Turkey to very much concentrate on its border with Syria.

CAGAPTAY: Absolutely.

KEILAR: Is that your expectation?

CAGAPTAY: Absolutely. Yes, I think the first phase of cooperation is going to be with the U.S. and other Western intelligence agencies to find out who helped these guys carry out these horrific crimes. So Identify the group. That's the first phase. The second phase is going to be sealing the border shut. It's a very porous border. It's been historically a smuggling route and I think U.S. will need -- I think turkey will need U.S. assistance with technology, hardware, drones, to seal that border tight shut.

And then you will talk about further cooperation against ISIS inside Syria. It's very likely we're going to see Turkish airstrikes against the Islamic State. Turkish President Erdogan who's known as a strong man, right-wing president, will not let ISIS get away with this. He will come down but he's also going to work with the United States. But there is a -- there's a trick here. There's also Russian piece.

The Russians basically control the air space of northern Syria. Turkey and Russia are in a conflict after Turkey shot down the Russian plane in November which had violated Turkish air space and so now Turkish planes cannot fly into Syria, Turkish troops cannot be deployed, so Turkey has to come to (INAUDIBLE) with Russia if it wants to deploy troops into Syria.

KEILAR: All right. Soner, Clarissa, Tom, Chairman Rogers, thanks to all of you.

And coming up, Donald Trump says water boarding suspected terrorists is one way to defend the U.S. from attacks like the one in Istanbul. We'll bring you reaction from the presumptive Republican nominee.

(BEGIN VIDEO CLIP)

DONALD TRUMP (R), PRESUMPTIVE PRESIDENTIAL NOMINEE: Folks, there is something going on that is really, really bad. All right? It's bad.

(END VIDEO CLIP)

(COMMERCIAL BREAK)

[17:51:24] KEILAR: Donald Trump is responding to this terror attack by repeating his proposal to water board suspected terrorists.

Sara Murray is following this story. What can you tell us, Sara?

SARA MURRAY, CNN POLITICS CORRESPONDENT: Well, Brianna, Donald Trump has made being tough on terror really a key part of his campaign platform. He's carried that on in the wake of the terror attacks in Turkey. But his recommendations are drawing some criticism including from members of his own party.

(BEGIN VIDEOTAPE)

MURRAY (voice-over): Donald Trump pushing for a muscular response in the aftermath of the terror attack in Turkey.

TRUMP: Folks, there's something going on that's really, really bad. All right. It's bad. And we better get smart. And we better get tough. Or we're not going to have much of a country left. OK. It's bad.

MURRAY: The presumptive GOP nominee renewing his call to bring back so-called enhanced interrogation techniques, including water boarding, to help defend the United States from its enemies.

TRUMP: So we can't do water boarding, which is -- it's not the nicest thing but it's peanuts compared to many alternatives. Right? You have to fight fire with fire.

MURRAY: A suggestion that was quickly criticized by 2008 GOP nominee and former prisoner of war, John McCain. SEN. JOHN MCCAIN (R), ARIZONA: According to the Geneva Conventions,

it's a war crime. But perhaps more importantly than that if you're not into academics and history is it doesn't work.

MURRAY: All of this in stark contrast to Hillary Clinton who emphasized a diplomatic approach, calling for closer cooperation with allies in Europe and in the Middle East. In a statement she said, "The attack only strengthens our resolve to defeat the forces of terrorism and radical jihadism around the world. And it reminds us that the United States cannot retreat."

Meanwhile, Trump managed to set off another controversy Tuesday as he hammered U.S. trade deals in particularly graphic term.

TRUMP: The Transpacific Partnership is another disaster done and pushed by special interests who want to rape our country.

MURRAY: And he deepened his rift with the traditional GOP orthodoxy of supporting free trade.

TRUMP: Globalization has made the financial elite who donate to politicians very, very wealthy. I used to be one of them.

MURRAY: But the elite struck back. The usually Republican friendly U.S. Chamber of Commerce taking to Twitter to say, "Under Trump's trade plans we would see higher prices, fewer jobs and a weaker economy."

And Trump returned the fire.

TRUMP: The U.S. Chamber of Commerce is totally controlled by the special interest groups. They want to have TPP, Transpacific Partnership. One of the worst deal. It will be the worst deal since NAFTA.

MURRAY: All of this as Clinton slammed Trump as late to the party on trade issues and made her own pitch to struggling Americans.

HILLARY CLINTON (D), PRESUMPTIVE PRESIDENTIAL NOMINEE: I am sympathetic to a lot of the people attracted by Trump's message who are feeling really left out and left behind. I am not sympathetic to the xenophobia, the misogyny.

MURRAY: President Obama backing up Clinton today, saying Trump's trade rhetoric is hardly populism.

BARACK OBAMA, PRESIDENT OF THE UNITED STATES: They don't suddenly become a populist because they say something controversial in order to win votes.

(END VIDEOTAPE)

MURRAY: Now it's pretty clear Donald Trump has no plans to back off his jabs against the GOP establishment. At a campaign event today he said his GOP rivals who pledged to support whoever the nominee was and have not endorsed him should not be allowed to run for public office ever again so the fight among the GOP continues -- Brianna.

[17:55:06] KEILAR: All right, Sara Murray, thank you.

And coming up, much more of our breaking news as investigators study the shocking video images from the Istanbul airport attack. There are new details on the massacre.

Which U.S. intelligence suggests bears all the characteristics of ISIS terrorism? Is the U.S. also at risk?

(COMMERCIAL BREAK)

KEILAR: Happening now, breaking news. Most likely ISIS. Officials in the United States and Turkey say the terror group is the prime suspect in the airport attack. I will ask the chairman of the Senate Homeland Security Committee what he learned in a high-level briefing a short time ago.

U.S. response. The CIA chief is warning that what happened in Istanbul could happen here. And that ISIS may be plotting some more attacks right now.