Mark Preston is CNN's executive director of political programming and senior political analyst. He hosts "Full Stop with Mark Preston" on SiriusXM POTUS 124. The full interview can be heard on Saturday at 12 p.m. ET, Sunday at 1 a.m. ET, and Sunday at 5 p.m. ET. Follow him at @prestonCNN .

(CNN) Without hesitation, George Shultz leaned forward in his chair and named two issues in a solemn tone: nuclear weapons, climate change. The subjects may seem oddly paired, unless you knew I had just asked him, "What keeps you up at night?"

"Well, there are two things that can wipe us out," said Shultz . "One is nuclear weapons and the other is climate change. I worry about both of those things."

It was surreal to hear Shultz, credited with helping President Ronald Reagan bring an end to the Cold War, offer such a blunt assessment about two issues dominating news coverage. Except Shultz didn't raise the alarm about nuclear war and climate change this week. Rather, Shultz, who has held the positions of secretary of state, secretary of treasury, secretary of labor and director of the office of management and budget, delivered this warning in late May during a rare interview in his office at Stanford University's Hoover Institution

While President Donald Trump's rhetoric on North Korea may be a bit extreme, he appears to recognize the existence of threat -- even if he hasn't developed a clear strategy to address it. However, when it comes to the issue of climate change, there is much he has to learn. My unsolicited advice to our President: Shultz has a wealth of information and knowledge. He may just be able to offer insight into how to deal with some of these difficult subjects.

Wealth of knowledge

At 96 years old and 2,500-plus miles away from Washington, Shultz is still dialed into the major problems facing the US government, and he continues to work to try and find solutions. As President Ronald Reagan's secretary of state, Shultz played point on negotiations with the then-Soviet Union, China, the Middle East and many other hot spots and crises the United States encountered in the 1980s.

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The challenges and problems may have changed over the years, but the actors have not. That is why I was surprised when Shultz said his telephone was not ringing off the hook with calls from congressmen and the Trump administration seeking his advice and expertise.

"Actually, I don't get very many requests from Washington," Shultz said in an interview that will air for the first time this weekend on SiriusXM's "Full Stop with Mark Preston." I don't think about it much. I got plenty to do here."

Drawing a red line

"Well, North Korea is a huge problem, and there isn't any obvious solution," he said. "I think we have to work at it, and you have to be able to work at it with China. And I know from contacts I have that China is ready to work on it. But it has to be done on a quiet basis, where you have two or three people on each side who quietly work at it and are authoritative and can make deals."

This week, it was reported North Korea has produced a miniaturized nuclear warhead that fits inside its missiles. This prompted Trump to warn that "North Korea best not make any more threats to the United States. They will be met with fire and fury like the world has never seen."

Sen. John McCain, R-Arizona, questioned Trump's warlike statement. "Don't threaten unless they're ready to act, and I'm not sure President Trump is ready to act," he said.

In the May interview, Shultz seemed to channel McCain's thoughts on making bold declarations -- the former secretary of state said he learned as a young Marine not to make them unless you were willing to follow through.

"I remember the day the sergeant handed me my rifle and said, 'Take good care of this rifle. This rifle is your best friend,'" said Shultz, recalling his time in boot camp. "'And remember one thing, never point this at anybody unless you're willing to pull the trigger. No empty threats.' I told that story to President Reagan. He liked it, and he said, 'We'll be very careful. We'll mean what we say, and people (will) know that we're serious, we're willing to pull the trigger.' And if people know that, you probably don't have to pull it."

Shultz added, "Words matter if ... they're serious words. If you draw a red line and then you don't do anything when it's crossed, your words lose their meaning and nobody pays attention anymore."

US-Russia relations & nuclear destruction

As secretary of state, Shultz was in the middle of the diplomatic effort to try and strengthen relations between the United States and the Soviet Union, as well as put in place arms control agreements. Now, as he views the current relations between the United States and Russia, Shultz said there needs to be a better working arrangement between the two countries. But he added that Washington should send a strong signal to Moscow about Ukraine.

"Somehow we need to find our way to having a decent problem-solving type of relationship with Russia, and I think the way is, first of all, to put a big red light up in the Ukraine," Shultz said. "We still haven't provided the Ukrainian armed forces with lethal weaponry. We should do that, in my opinion, and let Russia see that there is a big stop sign. When they see that, maybe they'll change their tune a little and then we can start to engage."

Perhaps some people were listening. The New York Times and The Washington Post reported earlier this month that arming Ukraine is under consideration, but it is unclear if Trump will follow through.

Unlike just about everybody -- Republicans and Democrats alike -- the President is reluctant to criticize Russia, and he recently said that US-Russia relations are at "an all-time & very dangerous low." Trump cast blame on Congress for forcing him to sign a very tough sanctions bill punishing Russia, saying it will only contribute to the deteriorating situation. Trump's unwillingness to publicly take on Russia comes as multiple congressional committees and an independent counsel investigate to see if his campaign colluded with Russia in the 2016 presidential election.

Shultz, for his part, has never kept his eye off of his goal of reducing the number of nuclear weapons the United States and Russia stockpile. He recalled the now-historic 1986 Reykjavík, Iceland, meeting that Shultz attended with Reagan, President of the Soviet Union Mikhail Gorbachev and Soviet Foreign Minister Eduard Shevardnadze that led to the reduction of nuclear weapons.

"(S)ince that time, the numbers of nuclear weapons in the world are roughly a third of what they were then," Shultz said. "So we got big reductions, and we ought to keep that going. Now it seems that it's going the other way, there's a proliferation process taking place.

Shultz added, "Well there's a lot of loose talk about nuclear weapons, and so people don't appreciate the implications of using them. When we had the first Reagan and Gorbachev meeting in Geneva, out of it came a statement , 'A nuclear war can never be won and must never be fought.' It was a big agreement between them ... if we could get Mr. Putin and Mr. Trump to have a statement, of similar sort, that would be a big step."

For Shultz, the danger that nuclear weapons pose is not viewed with the same sense of urgency as it once was and needs to be.

The other looming threat: climate change

Shultz's clarion call on reducing nuclear weapons is only matched by his appeal for world leaders to take action on climate change and continue to fund research and development with both public and private sector investments.

"Well, the CO2 that's in the atmosphere, it's going to stay there, but we can do a better job of keeping it down," said Shultz, who noted the advances that have been made in perfecting solar power and electric cars.

Shultz acknowledged part of the problem with addressing climate change is that the issue has become so politicized, it is difficult to reach a consensus. Oftentimes, Shultz said he thinks about how Reagan addressed the issue.

"In the mid-80s, we found a lot of scientists saying the ozone layer is depleting, and there were some who doubted it," he said. "But they all agreed that if it happened, it would be a catastrophe. So President Reagan was convinced that the people who were worried were right."

"Instead of doing what we now do, which is try to destroy the people who don't agree with you, (Reagan) put his arm around them and said 'We respect you, but you do agree if it happened, it would be a catastrophe? So, why don't we take out an insurance policy?'" he continued. "That didn't get them on our side, but it got them off our back. Out of it we got the Montreal Protocol, which people now pretty much agree came along just in time, and it worked. So that's the way to go about things." The Montreal Protocol, signed in 1987, was the first international treaty aimed at protecting the atmosphere from the effects of global warming.

Lasting legacy

Shultz's office at the Hoover Institution is like a small museum featuring pictures of world leaders and awards he received over the years for his service to three separate presidents. But he considers his family life to be among his greatest achievements.

"Well, I have five children, I have 11 grandchildren, and now I have five great-grandchildren," he said. "And that's my legacy."

Below are some of the highlights of my interview with Secretary Shultz. This Q&A has been edited for brevity, clarity and flow.

Threats that can wipe us out

Mark Preston: Secretary Schultz, what keeps you up at night? When you're looking around the globe, what are some of the things that concern you when you're thinking about your kids, your grandkids, your great grandkids?

George Shultz: Well, there are two things that can wipe us out. One is nuclear weapons and the other is climate change. I worry about both of those things. And I now have five wonderful great-grandchildren, and I watch them, they're so much fun. They're curious about everything, and I say to myself, "What kind of world are they going to inherit? And what can I do to make it a little better?"

Preston: What kind of a world do you think they're going to inherit?

Shultz: Well, we're not paying attention to nuclear weapons anymore. People have forgotten how deadly they are. But I hope we don't have to get awakened by their use. I keep working on that subject, and maybe it will come back and people will be aware of how totally unacceptable they are. A nuclear weapon dropped somewhere in the Bay Area (San Francisco/Oakland) incinerates the area; there's nothing left. ... They have immense destructive power. If you have an outbreak, say between India and Pakistan, and a few weapons are used back and forth, it isn't only India and Pakistan that get wiped out, it puts a cloud around the globe. And you can have global cooling on a big stage and that can make vegetation hard to grow.

India & Pakistan

Preston: Should we be very concerned about the relationship between those two countries?

Shultz: They are at odds with each other, particularly up at the Kashmir. We had a group of Indian and Pakistani former generals and foreign minister types here for a couple of days just to talk about it. And one of the interesting things I said, "Have you ever tried to calculate the cost in your income per capita of the enmity that you have? You live right next to each other, yet you have practically no trade. But the possibilities are great." So, there was an economist from each country there ... they agreed to make a study together and it was astonishing how big the cost to their income ... and you think they would be interested in anything that would increase their income per capita. If they could cool it between them and encourage trade and mutual economic activity, they could have a big boost.

China

Preston: The warming of relations between China and our current government -- good move?

Shultz: Absolutely, it is a good move, and you need to develop counterparts, a feeling of trust between you as human beings. When you do that, you can have candid conversations, because the other side knows you're not going to blurt it to the press ... and embarrass the person you're talking to. So, you need to develop that capability.

Russia

Preston: How do you see the state of play between Russia and the United States?

Shultz: Somehow we need to find our way to having a decent problem-solving type of relationship with Russia, and I think the way is, first of all, to put a big red light up in the Ukraine. We still haven't provided the Ukrainian armed forces with lethal weaponry; we should do that ... and let Russia see that there is a big stop sign. When they see that, maybe they'll change their tune a little and then we can start to engage. But between the United States and Russia, we have most of the nuclear weapons and we need to talk about it. When we had the meeting with Reagan and I and Gorbachev and Shevardnadze at Somehow we need to find our way to having a decent problem-solving type of relationship with Russia, and I think the way is, first of all, to put a big red light up in the Ukraine. We still haven't provided the Ukrainian armed forces with lethal weaponry; we should do that ... and let Russia see that there is a big stop sign. When they see that, maybe they'll change their tune a little and then we can start to engage. But between the United States and Russia, we have most of the nuclear weapons and we need to talk about it. When we had the meeting with Reagan and I and Gorbachev and Shevardnadze at Reykjavík ,the numbers of nuclear weapons in the world are roughly a third of what they were then. So we got big reductions and we ought to keep that going. Now it seems that it's going the other way; there's a proliferation process taking place.

Lack of trust

Preston: As we (talk) about Washington right now, and the dysfunction between Democrats and Republicans, do you think -- and I don't think this is exclusive to either party -- that perhaps people aren't taking the moral high ground on issues? That they're just politicizing things?

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Shultz: It's been a long time since I was there. But I know quite a few of the people and ... a friend of mine who is a senator said to me, "(Defense Secretary) Jim Mattis came to my office and asked me my opinion about things." And this person couldn't say enough about Jim Mattis. That's the old-fashioned way. Go to the other guy, ask their opinion, be interested, be a friend. That works.

Preston: Is it frustrating when you don't see that happen?

Shultz: It's frustrating, but I understand in Washington, hardly anyone lives there anymore. Their families aren't there. In the old days we would get together on weekends, and nothing heavy, just get to know each other and trust each other.

Leadership advice

Preston: When you look at all of presidents that you've served under, you must have taken away some kind of positive advice or element that helped guide you through your own life.

Shultz: Well, I think the big lesson you learn from looking at the success people had was the importance of a strategy of knowing where you're trying to go, and then doing a good job of execution.