The following is a script from "John Brennan" which aired on Feb. 14, 2016. Scott Pelley is the correspondent. Robert G. Anderson, Pat Milton and Aaron Weisz, producers.
The ISIS assault on Paris and the ISIS-inspired massacre in San Bernardino, California, share a disturbing fact, no one saw them coming. Today, the biggest terrorist threat to the United States is not like al Qaeda. ISIS is wealthy, agile, sophisticated online, and operates freely in a vast territory of its own. It prefers to be called the Islamic State. The U.S. government calls it ISIL. Reporters tend to call it ISIS for the Islamic State in Iraq and Syria. But whatever the name, it has the manpower, means and ruthlessness to attack the U.S. The man who is supposed to stop that attack is John Brennan, the director of the CIA. And tonight, in a rare interview, we talk to Brennan about a world of trouble and we start with the most pressing danger.
Scott Pelley: Is ISIS coming here?
John Brennan: I think ISIL does want to eventually find it's, it's mark here.
Scott Pelley: You're expecting an attack in the United States?
John Brennan: I'm expecting them to try to put in place the operatives, the material or whatever else that they need to do or to incite people to carry out these attacks, clearly. So I believe that their attempts are inevitable. I don't think their successes necessarily are.
Scott Pelley: Can you explain to the folks watching this interview why these people wanna kill us? How does attacking the United States further their interests?
John Brennan: Yea, I think they're trying to provoke a clash between the West and the Muslim world, or the world that they are in as a way to gain more adherents. Because what they are claiming is that the United States is trying to take over their countries which is the furthest thing from the truth.
Paris was a failure of intelligence. All but one of the eight terrorists were French citizens, trained by ISIS in Syria. They returned, unnoticed, and attacked six locations killing 130 people.
Scott Pelley: What did you learn from Paris?
John Brennan: That there is a lot that ISIL probably has underway that we don't have obviously full insight into. We knew the system was blinking red. We knew just in the days before that ISIL was trying to carry out something. But the individuals involved have been able to take advantage of the newly available means of communication that are--that are walled off, from law enforcement officials.
Scott Pelley: You're talking about encrypted Internet communications.
John Brennan: Yeah, I'm talking about the very sophisticated use of these technologies and communication systems.
Scott Pelley: After Paris you told your people what?
John Brennan: We gotta work harder. We have to work harder. We need to have the capabilities, the technical capabilities, the human sources. We need to be able to have advanced notice about this so that we can take this-- the steps to stop them. Believe me, intelligence security services have stopped numerous attacks-- operatives-- that have been moved from maybe the Iraq to Syria theater into Europe. They have been stopped and interdicted and arrested and detained and debriefed because of very, very good intelligence.
But the failure in Paris allowed ISIS to attack with bombs and assault rifles. And Brennan told us there's more in their arsenal.
Scott Pelley: Does ISIS have chemical weapons?
John Brennan: We have a number of instances where ISIL has used chemical munitions on the battlefield.
Scott Pelley: Artillery shells.
John Brennan: Sure. Yeah.
Scott Pelley: ISIS has access to chemical artillery shells?
John Brennan: Uh-huh (affirm). There are reports that ISIS has access to chemical precursors and munitions that they can use.
The CIA believes that ISIS has the ability to manufacture small quantities of chlorine and mustard gas.
Scott Pelley: And the capability of exporting those chemicals to the West?
John Brennan: I think there's always the potential for that. This is why it's so important to cut off the various transportation routes and smuggling routes that they have used.
Scott Pelley: Are there American assets on the ground right now hunting this down?
John Brennan: The U.S. intelligence is actively involved in being a part of the effort to destroy ISIL and to get as much insight into what they have on the ground inside of Syria and Iraq.
John Brennan has worked at the CIA for most of 36 years, ever since he saw a want ad while he was in graduate school. And he was a high-ranking executive here during the recent controversies, Iraq's phantom weapons of mass destruction and 9/11.
Scott Pelley: Do you think of water boarding as a dark time in the history of your agency?
John Brennan: Sure. Waterboarding was something that was authorized. It was something that I do not believe was appropriate. It is something that is not used now and as far as I'm concerned will not be used again.
Scott Pelley: You were in management here at the time. You didn't stop it.
John Brennan: No. I had expressed to a few people my misgivings and concerns about it but no, I did not, you know, slam my fists on a desk. I did not go in and say we shouldn't be doing this. I think long and hard about what I maybe should have done more of at the time. But it was a different time. The ashes of World Trade Center were still smoldering. We knew that other waves of attacks were planned and some that were underway.
Scott Pelley: In the year or so before 9/11 the CIA had a covert action plan to attack al Qaeda in Afghanistan. The administration at that time said, "Don't do that. We have time. We'll deal with this later." And then 9/11 happened. Is this administration making the same mistake now?
John Brennan: Well you know there are a lot of options that are presented to this administration as well as to previous administrations and the president has pursued what he believes is appropriate for us to do in order to protect the citizens of this country.
Scott Pelley: What do you think our policy would be after an ISIS-directed attack in the United States?
John Brennan: If there's a major attack here and we had ISIS fingerprints on it certainly this would encourage us to be even more forceful in terms of what we need to do.
Scott Pelley: If our policy after an attack in the United States would be to be more forceful, why isn't that our policy now before an attack?
John Brennan: Well, I think we're being as forceful as we can be in making sure that we're being surgical though as well. What we don't want to do is to alienate others within that region and have any type of indiscriminate actions that are going to lead to deaths of additional civilians.
The CIA Brennan leads from Langley, Virginia, looks nothing like the agency he joined. It's grown significantly but the numbers are secret. CIA fights with its own ground troops and has an air force of drones. The complexity of threats today is unprecedented; hacking, the emergence of a more aggressive China, North Korea, Russia and Iran and countries failing all across the Middle East.
Scott Pelley: In addition to Syria you are now dealing with failed states in Libya, Somalia, Yemen. How do you develop intelligence in all of these countries where the U.S. has no presence?
John Brennan: We need to be able to operate in areas that are denied to us. We find a way to have our eyes and ears there so that we can inform our policy makers. I do think though that this is going to be more and more a feature of the future. And we here at CIA are looking at how we need to enhance our expeditionary capabilities and activities because we need to be on the front lines.
Scott Pelley: Well do you imagine setting up CIA bases, covert bases in many of these countries?
John Brennan: I see CIA needing to have the presence as well as an ability to collect intelligence and interact with the locals. And we are in fact doing that in a number of those areas.
Scott Pelley: Who around here has the authority to OK a drone strike?
John Brennan: I know there are a lot of reports about the CIA's role and involvement on that. And I think as you can understand I'm not going to address any of those reports about CIA's covert action activities.
Scott Pelley: Do you have to accept the deaths of civilians when making a decision about using these weapons? Do you have to say, "There are likely to be civilians killed here but it's worth it?"
John Brennan: Well ya know in war there is what's called the law of armed conflict that allows for proportional collateral, collateral being civilian deaths. I must tell you that the U.S. military and the U.S. government as a whole does an exceptionally, exceptionally strong job of minimizing to the greatest extent possible any type of collateral damage.
But it isn't necessarily a shooting war that worries Brennan most. His CIA is facing a new front in cyber. And to focus on it he set up the agency's first new directorate in more than 50 years.
John Brennan: That that cyber environment can pose a very, very serious and significant attack vector for our adversaries if they want to take down our infrastructure, if they want to create havoc in transportation systems, if they want to do great damage to our financial networks. There are safeguards being put in place. But that cyber environment is one that really is the thing that keeps me up at night.
Scott Pelley: Do other countries have the capability in turning the lights off in the United States?
John Brennan: Having the capability but then also having the intent are two different things. I think fortunately right now those who may have the capability do not have the intent. Those who may have the intent right now I believe do not have the capability. 'Cause if they had the capability they would deploy and employ those tools.
Scott Pelley: A few months ago your personal emails were hacked. What did you learn from that, director?
John Brennan: It shows that there are ways that individuals can get into the personal emails of anybody.
Scott Pelley: Is privacy dead?
John Brennan: No. No. Privacy should never be dead.
Scott Pelley: Yea, I know it shouldn't be. But is it, in fact, with these hacktivists, with these nation-state actors, with all the things that we've learned about government snooping all around the world, isn't it effectively dead?
John Brennan: You know, it's interesting that people always point to the government or others in terms of the invasion of privacy. But--
Scott Pelley: Any government
John Brennan: --yeah, but individuals are liberally giving up their privacy, you know, sometimes wittingly and sometimes unwittingly as they give information to companies or to sales reps. Or they go out on Facebook or the various social media. They don't realize though that they are then making themselves vulnerable to exploitation.
Scott Pelley: When your secure phone rings in the middle of the night what what's your first thought?
John Brennan: It's usually one of two things. One, its bad news that something tragic has happened to a CIA officer or to U.S. personnel. Or there's been a terrorist attack somewhere of significance. And so when I reach for the phone I, you know, say a short prayer that it's not that. The other option is that I'm being asked to make a decision in the middle of the night on something that may have life and death implications. Could be something related to a covert action program.
Scott Pelley: Have officers died on your watch?
John Brennan: Yes. Yes. Not long after I came to the agency we had an officer, a former Army Ranger, went back out to Afghanistan. In the middle of the night, he heard an explosion at the compound next to his where his Afghan compatriots were sleeping. He grabbed his gear, he went over there. Another explosion took place. Rather than taking cover he went right to the middle of the fight and started to drag his wounded Afghan partners out of harm's way. He was hit twice. Continued to fire. Then as he was continuing to protect his colleagues and comrades, a hand grenade landed not too far from him and he was mortally wounded.
Brennan told us that he has gone to Dover, Delaware, to receive the remains of his fallen. But he can only go when he won't be seen, so no one will connect the body under the flag with the CIA. At headquarters, anonymous stars are carved for the dead. 113 in all, 31 since 9/11. And Brennan presides over an annual memorial for families.
John Brennan: We have family members of agency officers who died in the 1950s whose grandchildren, grandnieces and nephews come back here in order to feel a part of this agency. So it's a great, great honor to be a part of this organization where, again, selfless men and women of the agency have done their absolute best. Have we made mistakes? Yeah, we have. Do we need to be held accountable for them? Yeah. But let's not forget the sacrifices that have been made in the name of CIA.