The following is a transcript of an interview with retired Lt. Gen. H.R. McMaster, former Trump White House national security adviser and CBS News contributor, that aired on Sunday, October 2, 2022.

MARGARET BRENNAN: The Trump administration’s 2017 national security adviser, retired Lt. Gen. HR McMaster, joining us. HR, thank you for keeping us informed of what is happening in Ukraine with the Russian invasion. I want to hear your reaction to what Defense Secretary Austin called a significant development on the battlefield over the past 48 hours. What do you see and what are Vladimir Putin’s next steps?

LT. HR GENERAL MCMASTER: Hey, good morning, Margaret. Nice to be with you. Well, this is a huge victory for the Ukrainians. And this is a victory that I think they can turn into a cascading series of defeats for Russian troops. This is the encirclement of Liman and – and the Russian troops are retreating, but also, in the last two days, the Ukrainians also simultaneously defeated the Russian – Russian counterattack and also advanced further south near the strategically important city of Kherson. And I think, Margaret, that we may actually be on the brink of – a real collapse of the Russian military in Ukraine, a moral collapse. And I think they’re really at a tipping point. If you look only at the number of losses, then at the huge territory that they are trying to defend, and now, of course, Russia is trying to mobilize conscripts and send them to the front unprepared. And I think it’s very important to also understand that these forces that are now fully retreating from Lyman were really the first phase of the mobilization. Remember when Putin tried to recruit more and more people, paying about three times the average salary, to get the so-called volunteers to come forward. These forces were hastily prepared, thrown to that front, and these are the forces that are collapsing now.

MARGARET BRENNAN: Well, when it’s happening on the battlefield, rhetorically, you hear President Putin turning up the volume, making that nuclear threat again on Friday, and there was another Russian leader talking about using low-yield nuclear weapons. It is unclear what the reaction of NATO or the US would be if Russia used tactical nuclear weapons on the battlefield in Ukraine. What do you think it should be?

LT. GENERAL HR MCMASTER: Well, I think the message to him is that if you use a nuclear weapon, it will be a suicide weapon. And the response of NATO and the United States should not be nuclear. First of all, I would say, Margaret, that he is under extreme pressure. I mean, you have the battlefield failures that we talked about, but mobilization also fails. I mean what he did is he mobilized almost 300,000 people to leave the country. These–these are people who fled to neighboring countries to–to avoid this–this draft. And the Russians are now saying, well, I thought it was a special military operation, that Putin said, hey, leave it to me, don’t worry about it. Now he is going to them to save him with this mobilization and what you see among the hyper-nationalist group of bloggers and even in the state media is the accusation of the military. And the fact that the military is returning to Putin, saying: hey, it’s not our fault. We just need more troops. So, it’s to this cycle that he responds with the only quiver he has left, which is to, you know, threaten to use nuclear weapons. But, I’ll tell you, Margaret, I don’t think nuclear weapons can be used there, you know. Therefore, I believe that this should be taken seriously. We must, but we must not let that scare us in terms of supporting the Ukrainians.

MARGARET BRENNAN: Yes. Well, he has another weapon, which is, of course, energy and the tracking of this potential sabotage on the gas pipeline. I also want to ask you about when you were in office in 2017 when the US first transferred offensive weapons to Ukraine, I remember when you were put in the position of having to explain the conversation at the time… President Trump met with Russian officials in the Oval Office, where he mentioned classified information. And you – you called it completely appropriate at the time. Given what’s going on now with this classified materials investigation at Mar-a-Lago, have you ever been uncomfortable with the former president’s handling of classified information?

LT. HR GENERAL MCMASTER: Well, Margaret, remember, I left in February, March of 2018. But while I was there, I didn’t see any problems handling classified information. And what you’re talking about is actually a meeting where the president didn’t release classified information, but somebody released it. And then they printed it in the newspaper. So classified information — I think it’s important to go back to that period, and that giving the Ukrainians the Javelin defense capability was very important, and the argument I made to President Trump at the time was, hey, these people who say to you, that giving Ukraine a defense capability is a provocative matter, in fact, Putin is provoked by weakness. And this argument convinced him. And I think this argument is still relevant today. I mean, Putin is facing these difficulties, and I think it’s time to lift some of the restrictions that we put on ourselves in terms of supporting the Ukrainians, and I’m talking about long-range surveillance capabilities tied to the range of a precision strike. And that’s really what they need, I think, to keep the momentum going militarily at this stage.

MARGARET BRENNAN: I have a follow-up question on that, but just to ask the question that I asked you, it wasn’t, were you ever uncomfortable with manually handling classified information?

LT. HR GENERAL MCMASTER: No, you know Margaret, there were systems in place. I don’t know what happened to these systems. But- but- but I was never embarrassed about it while I was there. But you know, it was a long time ago.

MARGARET BRENNAN: Okay. I know when you are in office you never like to answer wrong facts. But you are not in office, so was Vladimir Putin so committed to this invasion that he would go along with it no matter what?

LT. HR GENERAL MCMASTER: I don’t think so. Think about all the support we have now given to Ukrainians. What if we had done this a few years ago? I think that Putin could draw a conclusion. Well, Ukraine cannot be taken for an acceptable price. And of course he was wrong about all the assumptions leading up to the invasion. And this was proved by courageous Ukrainians who defend their sovereignty. But I think that holding back the rejection was a failure for us. I mean, in a lot of the actions that we did in the months leading up to the invasion, I think, unintentionally green-lighting, you know, pulling our forces out of the Black Sea, listing all the things we weren’t going to do. And I think the administration has recovered from that very well. But I think, Margaret, now is the time to lift the restrictions on the support that the Ukrainians give us, so that they can finish this fight on their own terms.

MARGARET BRENNAN: Okay, HR McMaster, thank you very much for your insight today. We’ll be back in a moment.