The following is a transcript of an interview with National Security Adviser Robert O'Brien that aired Sunday, February 23, 2020, on "Face the Nation."

MARGARET BRENNAN: That's the president at a Friday rally in Las Vegas claiming that reports of Russia interfering in his favor was democratic "disinformation." When we were in Las Vegas Saturday, I spoke with the White House National Security Adviser Robert O'Brien, who was in our Washington studio. I asked him if he had assured the President that this particular US intelligence finding was real. He strongly disputed it.

NATIONAL SECURITY ADVISER ROBERT O'BRIEN: Well, I have not seen the finding. I think what he's referring to and what folks are talking about is a briefing that took place last week at the House Intelligence Committee that was leaked to the press. And I- I have not seen that report. I get this second hand, but from Republican congressmen that were in the committee, there was no intelligence behind it. I haven't seen any intelligence to support the reports that were leaked out of the House.

MARGARET BRENNAN: But the White House was briefed on February 14th. Were you not in that briefing when the president was informed?

O'BRIEN: Well, there's no briefing that I've received, that the president has received, that says that President Putin is doing anything to try and influence the elections in favor of President Trump. We just haven't seen that intelligence. If it's out there, I haven't seen it. I'd be surprised if I haven't seen it. The leaders of our- the IC have not seen it. So I- again, I don't know where this is coming from. I've heard these rumors and these leaks from Adam Schiff's committee, but I- I have not seen them myself and I've seen no intelligence along those lines.

MARGARET BRENNAN: But just to clarify, are you saying that Joseph Maguire, the former acting director of national intelligence, did not inform you about the U.S. Intelligence Committee's- community's findings?

O'BRIEN: No. I, look, I think- you know, and again, I- I don't want to get into private conversations in a- in a presidential daily brief, but I- I don't think Admiral Maguire was necessarily informed of what was going to happen at that hearing in the House either. And- and again, there's nothing that he's given up, no information Admiral Maguire gave us, Gina Haspel has given us- Director Haspel, Ambassador Grenell the new acting DNI, that comports with what was leaked out of that House Intel Committee. So I haven't seen it. The leaders of the intelligence community that I've spoken with haven't seen anything that comports with what was leaked out. But again, those leaks, I don't know if that's what the briefers told the House committee. I mean those were simply --

MARGARET BRENNAN: But- well, that- that's contradicted by reports that the director of national intelligence, Maguire, did brief White House officials. But more broadly, the FBI director at the beginning of the month, Chris Wray, testified that Russia continues to try to influence the elections mainly through social media manipulation. So this pattern of behavior has continued, Russia is undeterred. Are you denying that that is happening?

O'BRIEN: No, no. What I- look I- what I've heard from the FBI, you know- well, what I've heard is that Russia would like Bernie Sanders to- to win the Democrat nomination. They'd probably like him to be president, understandably, because he wants to- to spend money on social programs and probably would have to take it out of the military, so that would make sense. And- and look, the Russians have always tried to interfere with elections because they want to divide Americans. They want to undermine our democracy. But the idea that they want to- they want to influence the election and somehow cause the president to win, I just don't see it. But look, I think there are a number of countries: China, Russia, North Korea, Iran, that would like to influence our elections to- to get the candidate that they feel would be best for their country.

MARGARET BRENNAN: So you are saying that it is not, in fact, the U.S. intelligence community's assessment that Russia has a preference for President Trump?

O'BRIEN: I-I have not seen that. And- and again, why would they have a preference for President Trump, who is rebuilding our military, who is giving the Ukrainians lethal aid to fight Russian troops? So that doesn't make sense. Now, look, we want good relations with Russia. We'd like to have great relations with Russia. I haven't seen any intelligence that there's any active measures by the Russians to try and get the president re-elected. And- and we've got a simple message for the Russians or any other country that wants to- to meddle in our elections, whoever they're behind: stay out of our democratic elections. And- and we're doing everything we can. We're working with state and local officials. We're going, in many cases--

MARGARET BRENNAN: But you--

O'BRIEN: --to paper ballots to make sure that- that, you know, governments with ill intent can't hack secretary of state websites, can't get involved in our elections, change results. And we're going to work on election security very, very hard through- across the interagency in the federal government and also with our state and local partners.

MARGARET BRENNAN: Why not have the intelligence community testify in public about what they are seeing, so that the public can arm themselves, so that they can understand what is disinformation and what is fact?

O'BRIEN: Look I--

MARGARET BRENNAN: Why not declassify some of those?

O'BRIEN: I'd- I'd have no problem with that. And- and- but that's not my decision. And the intelligence community is- is very concerned and careful about sources and methods and I understand that. But I- I would personally have no problem with--

MARGARET BRENNAN: --But back in 20- back in 2016 in October of 2016, when Russia was doing this disinformation campaign, the Obama administration did declassify information at that time. So there is a precedent. Why doesn't the Trump administration do that?

O'BRIEN: --I think if there's intelligence that we can declassify that- that we can get out there all the better, because, again, we weren't in office in 2016 when- when the last election meddling took place and the administration did very little about it. And- and they- you know everyone admits that- that very little was done about it. We're in office now and we're doing everything we can across the interagency and- and with our state and federal and local partners to- to ensure that- that American ballots are secure, that- that are our- our ballot machines are secure, that tabulations are secure, that- that state, secretary of state websites are secure. We want to make sure that this is a free and fair election, that Americans select their next president, not some foreign country. And- and we're gonna do- and the president's been deadly serious about that.

MARGARET BRENNAN: Why was Joseph Maguire pushed out? Why did he leave? Are you 100 percent sure it had nothing to do with this congressional briefing?

O'BRIEN: Yeah, I- I- I look, I- I was there. So I- first of all, Joe Maguire wasn't pushed out. Joe Maguire's term, he was an acting- he was- he was serving under the Vacancy Act. He was acting and his term, I believe, was ending March 11th or March 12th, like two weeks from now. (00:07:31) So we're looking for a- a nominee that can be a terrific candidate, who can be nominated for this position. We needed someone who was Senate confirmed who could serve in the meantime. And we turned to a great ambassador, Rick Grenell, our ambassador to Germany. And- and he's stepping in on a temporary basis to- to serve in the role of acting DNI. We'll get a nominee out to the Senate as soon as possible. And- and look, I'm urging and the president's urging that the Senate will move quickly, that we can get a- a full time confirmed DNI in place long before the election. And this is an opportunity for the Senate to show that they can come together, get the business of the people done and get a- a- a DNI confirmed and in place. I think that'd be great. But Joe Maguire wasn't pushed out. We'd love to see Joe Maguire stay involved in the government. Joe- Joe had a- a great relationship with the president. I had a great relationship with him. We have a lot of respect for Joe Maguire. So- so the premise of your question that he was pushed out just isn't true. Joe Maguire was always planning on leaving within the next couple of weeks. So, you know, he- he did a great job. I had a really great relationship with him. (00:08:32) And I have a tremendous amount of respect for him, as does the president.

MARGARET BRENNAN: To be clear, Rick Grenell does not have an intelligence background. I want to quickly ask you, though, about Afghanistan. If the Taliban does not make good on its promise to pull back on violence, to sign this deal at the end of the month, is the president positioned to stop the troop withdrawal?

O'BRIEN: The president made it very clear the last time we were close to signing a deal with the Taliban and they- they engaged in some malign activity, they- they had a vehicle-borne IED that killed a number of people, including one American, and the president pulled back from signing the deal. We're hopeful that- that we can get to a- a place where the Afghans can talk with each other and negotiate some sort of resolution, a political resolution of the conflict. We've been there 19 years. It's time for us to stop bringing our- our sons and daughters home through Dover Air Force Base and dignified transfers. We've got to get out of- of the war in Afghanistan, but we're gonna do it in a way that protects American interests. So if the Taliban does not live up to their agreement on the reduction of violence plan, then we'll take a very care- careful look at it. And I think it'd be unlikely that we'd- we'd sign a peace treaty, but we're not going to reduce troops to a level below what is necessary to protect American interests and our partners in Afghanistan. I can assure you of that.

MARGARET BRENNAN: All right. Ambassador O'Brien, thank you for joining us.

O'BRIEN: Always great to be here, Margaret.

MARGARET BRENNAN: The Trump-appointed official overseeing US election security - Shelby Pierson - reported to Congress that Russia was interfering in the election and has shown a "preference" for President Trump but sources tell our Major Garrett there was bipartisan push back on her assertions and questions about the strength of the evidence. Congress has requested to see the underlying intelligence to back up that assessment, which as you heard, the National Security advisor said he had not seen. CBS stands by Major's reporting the President was told Russia was trying to help him win. We'll be back in a moment.