Editor’s Note: In a previous version of this transcript, Lieutenant Colonel Kristopher Geelan was incorrectly identified as Brian Hyland.

The following is a script from “The New Cold War” which aired on Sept. 18, 2016. David Martin is the correspondent. Mary Walsh, producer.

One of the key questions of this presidential campaign is who has the health and temperament to become the next commander-in-chief and assume the unthinkable power to use nuclear weapons. The Cold War as we knew it may be over, but both the U.S. and Russia still keep enough nuclear weapons on alert to end civilization. And now a new Cold War is brewing with both sides developing more sophisticated and more accurate weapons.

Tonight, we’re going to show you what this new Cold War looks like from inside the U.S. Strategic Command. STRATCOM, as it’s called, trains every day for the possibility of nuclear war and takes extraordinary measures to make sure that one person and one person only -- the president of the United States -- can give the order to launch a nuclear weapon.

USS Kentucky CBS News

The USS Kentucky rising to the surface off the coast of Hawaii. Nearly two football fields long, it is the deadliest engine of destruction in the American arsenal, able to carry almost 200 nuclear warheads atop the missiles loaded beneath those hatches. Commander Brian Freck is the captain.

Brian Freck: The warheads that can be carried on my missiles are extremely powerful.

David Martin: Compare them to the bomb that leveled Hiroshima.

Brian Freck: Much more powerful than that. Much more powerful than Hiroshima.

Up to 30 times more powerful and on any given day a number of these submarines are hiding somewhere in the world’s oceans ready to respond to a launch order from the president.

David Martin: When you’re out here are other countries looking for you?

Brian Freck: I always operate under the assumption that someone’s looking for me.

David Martin: Has anybody ever found you?

Brian Freck: No. Not even close.

David Martin: You sure?

Brian Freck: Yes, I am.

60 Minutes found the Kentucky but only because we had arranged a rendezvous to go aboard.

David Martin: If this boat were a country, you’d be a nuclear power.

Brian Freck: That’s true, yes sir.

David Martin: Does that ever give you pause to have all that power under your command?

Brian Freck: It’s a lot of responsibility but with that responsibility comes a lot of training and practice.

[”Dive, dive. All vents cycled. All vents shut.”]

Operating at a depth of 160 feet, the Kentucky’s crew practiced the procedures needed to launch its missiles.

[”Set condition one SQ for training. This is the captain. This is an exercise.”]

[”Set condition one SQ for training. Com weapons aye.”]

[”Stand up all missiles.”]

[”Chief Alaud, sound the general alarm.”]

[”Sound the general alarm, aye sir.”]

[”I have permission to fire. Com weapons aye.”]

Before that trigger can be squeezed, multiple keys -- including one that unlocks the missile tubes which take up approximately one-third of the ship -- have to be brought out from different safes.

Brian Freck: No one person can make a launch happen. So I have keys in my possession. Other members of the crew have keys in their possession.

One key is carried to the captain by two sailors – who both must hold it.

[”Captain, the launch is authorized.”]

And here’s the thing you need to know about the safe where that key is kept.

Brian Freck: No one on board has the combination. We get that combination with the launch order. That is my way of knowing that the president has ordered the launch, is when the combination he gives me opens that safe.

David Martin: The president literally gives you the combination to the safe that the key is in.

Brian Freck: Yes.

[”You have permission to fire.”]

[”Two weapons. We have permission to fire. Aye sir. Weapons con – you have permission to fire. “]

The Kentucky and other nuclear missile submarines, along with intercontinental ballistic missiles and nuclear bombers are under the command of Admiral Cecil Haney.

[”Your nuclear forces are capable of executing all assigned missions.”]

Head of the U.S. Strategic Command, Haney is the most powerful military officer you’ve never heard of – in command not just of the nation’s nuclear forces but its space satellites and cyber weapons as well.

[”There are no significant solar activity causing impact to satellite operations or communications.”]

His morning briefing at strategic command headquarters in Omaha, Nebraska, is classified above top secret.

[”Thank you. I appreciate the update.”]

That clock marked POTUS – short for president of the United States -- tells Haney what time zone President Obama is in -- in case he has to reach the commander-in-chief in a hurry.

David Martin: So who in the United States government has the authority to order the use of nuclear weapons?

Cecil Haney: Only the president of the United States has that authority.

David Martin: Does Congress have to approve?

Cecil Haney: No, Congress does not have to approve.

David Martin: So these really are the president’s own weapons.

Cecil Haney: It’s our nation’s weapons, with the president’s authority. Yes.

Haney took us to his global operations center, a top-secret facility three stories underground. If a missile were launched against the United States the warning would be received here and that clock would start ticking down.

Colonel Barbara Buls was the watch commander.

David Martin: I see this sign up here. Red Impact. Blue Impact time -- so red impact would be an enemy missile?

Barbara Buls: That is correct.

David Martin: And you would have a time.

Barbara Buls: We would have a time to impact. And blue impact would be any U.S. counterattack.

Lt. Col. Kristopher Geelan would pull out the options for a retaliatory nuclear strike.

Kristopher Geelan: My responsibility, as the STRATCOM nuclear strike adviser, is to be the expert on the Nuclear Decision Handbook and the alert status of all U.S. nuclear forces.

David Martin: The Nuclear Decision Handbook.

Kristopher Geelan: Yeah, also known as the Black Book.

David Martin: Black book. So, is there a copy of the Black Book down here?

Kristopher Geelan: There is. It’s in the safe down here, sir.

An identical copy of the black book is in that briefcase which follows the president wherever he goes.

David Martin: So he’s never away from the options.

Cecil Haney: That’s correct.

David Martin: And, would they tell him what kinds of weapons you would use, what targets you would hit?

Cecil Haney: They would be that specific, yes.

David Martin: Would they give him an estimate of casualties?

Cecil Haney: Yeah, we would have to give the president answers to a lot of different questions. That’s one that I would expect to get.

Admiral Haney would go to a room called the battle deck where he would talk directly to the president.

David Martin: And is this the phone you would use?

Cecil Haney: This is one of the phones that I might use, yes.

David Martin: Chairman of the Joint Chiefs of Staff, secretary of defense. I don’t see the man who controls . . .

Cecil Haney: You’re looking for the president.

David Martin: I am.

Cecil Haney: I can speak to the president directly from this microphone.

David Martin: And in a crisis how long does it take to get the president on the line?

Cecil Haney: Not very long.

If Russia launched a missile from a submarine off the coast of the United States it would take only minutes to reach its target.

David Martin: So how long, in fact, does the president have to make a decision?

William Perry: He has minutes. Seven – eight – nine – depending on details. But less than 10 minutes.

Former Secretary of Defense William Perry was a key architect of nuclear weapons during the Cold War with the Soviet Union.

David Martin: If the weapons can be launched within minutes does that mean we’re still in the same-old, hair-trigger--

William Perry: Yes.

David Martin: --standoff that we were during the Cold War?

William Perry: That’s right. And we still have launch on warning, the same policy we had then. We still have the same hair-trigger response.

David Martin: So what’s changed since the Cold War if we’re still on this hair-trigger alert?

William Perry: Fundamentally nothing has changed.

David Martin: But the numbers of weapons are much lower now than during the Cold War.

William Perry: The number of weapons are sufficient to destroy, obliterate all of civilization.

David Martin: Still?

William Perry: Still. It doesn’t take that many. We still have more than 1,000 nuclear weapons on alert ready to go. It doesn’t take 1,000 to destroy civilization.

At the end of the Cold War both sides pledged to point their missiles at the open ocean. But it would take just minutes to change back to real targets.

That provides a small hedge against an accidental war triggered by a false alarm of the kind Perry experienced in 1979 when a watch officer mistakenly inserted a training tape into a computer.

William Perry: It looked like 200 ICBMs were on the way from the Soviet Union to the United States. Happily we got that situation figured out before we had to go to the president. But had we not he would have received a call at 3 o’clock in the morning and said, “Sir you have seven or eight minutes to decide whether to launch those before these missiles land on our ICBM silos.

David Martin: And what was the fail-safe there? What stopped it from going to the president?

William Perry: What stopped it was an astute general who sensed something was wrong.

David Martin: You’ve had one serious case in 45 years, that would seem like a pretty good record.

William Perry: It only takes one – it only takes one.

Strategic command is building a new $1.2 billion headquarters but it won’t be any more able to survive a nuclear blast than the underground command center in the current headquarters.

That clock counting down the time to missile impact would also tell Admiral Haney how long he had to get out of there alive.

Barbara Buls: Safe escape time that you see indicated is the time left, remaining, for Admiral Haney, as the commander of U.S. STRATCOM to exit the battle deck to be able to make it to his commander support aircraft to be able to board that aircraft and continue to provide his advice to the president of the United States as his senior nuclear adviser.

On the tarmac at STRATCOM air crews drill to get take off in this airborne command post fast enough to escape incoming nuclear weapons. If Admiral Haney’s headquarters were destroyed and he didn’t make it out in time it would be up to Rear Admiral Andy Lennon to assume command and make sure the president -- and only the president -- could still give the order to launch nuclear weapons.

Andy Lennon: We are in voice communications with the president.

David Martin: Talking to the president personally?

Andy Lennon: Yes sir, so that way we are ensuring that we’re getting the president’s intent.

David Martin: How do you know it’s the President?

Andy Lennon: We have some very complex and secure procedures to authenticate the president and to be sure that we’re really talking to the president of the United States.

David Martin: So he can’t just tell you, “This is the president speaking?”

Andy Lennon: He can, but we will authenticate to verify that it is the president speaking.

David Martin: Once the president has given you that order, what do you do?

Andy Lennon: Then we would communicate that order to our strategic forces, our intercontinental ballistic missiles, our bombers or our submarines.

[”Chief Alaud, sound the general alarm.”]

[”Sound the general alarm, aye sir.”]

The order would be received on board the Kentucky and the crew would go through launch procedures they have practiced hundreds of times before.

Last year, the Kentucky actually fired an unarmed missile in a test flight which lit up the California sky and caused a brief UFO scare. Had it carried a real warhead, Stuart Miller, a young Air Force captain aboard the airborne command post would begin charting the unthinkable.

Unarmed missile in a test flight (www.PrestonNewman.com) Preston Newman

Stuart Miller: My main role is, is gathering information on nuclear detonations worldwide and then applying meteorological data to them, specifically winds, to figure out if there’s fallout, depending on the attributes of the detonation where the fallout’s going, how many people might be affected, who might be affected, things of that nature.

David Martin: So, you basically come up with a casualty estimate of . . .

Stuart Miller: Essentially, yes, that’s one of the things that, that I can provide.

David Martin: You must have looked at some pretty depressing scenarios.

Stuart Miller: We kind of do, yeah, yes.

David Martin: Have you ever had the conversation with yourself, well, what if the president issued an order to use nuclear weapons and I didn’t agree with it. Would I carry out that order?

Cecil Haney: The president expects me, as his combatant commander, to provide him the best military advice I have. So he would expect me to voice my opinion.

David Martin: You would have a voice but if you disagreed with a decision . . .

Cecil Haney: I’m a military man and we follow the orders of our commander-in-chief.

So what are the chances the next president would actually have to make the fateful decision whether to use nuclear weapons? It’s greater than you might think. That part of the story next Sunday on 60 Minutes.