The following script is from "America's Missile Fields" which aired on April 27, 2014, and was rebroadcast on July 13, 2014. Lesley Stahl is the correspondent. Andy Court, producer.
The last time many of us thought about our nation's big land-based nuclear missiles was probably during the Cold War. But today, there are nearly 450 of these giant Minuteman-3s, as they're called, tucked away in underground silos, ready to launch, on the president's command.
The entire Air Force chain of command of a missile base responsible for one-third of our land-based missiles was removed last March because of a scandal involving drugs and cheating on tests.
As Lesley Stahl first asked after that scandal broke: What's going on? Why so much turmoil in the missile corps? Who's minding the nukes? And where are these weapons of mass destruction?
Flying over the plains of Wyoming in an old Huey helicopter, we came upon a small fenced-in lot. It didn't look like much.
Carl Jones: So that's it right there.
Air Force Colonel Carl Jones told us that, underneath the concrete, near that white pole, there's a Minuteman 3 missile. It's one of the deadliest and most powerful weapons on the planet.
Lesley Stahl: So is that particular missile armed right now with a nuclear warhead?
Carl Jones: It is.
The warhead on each of these land-based missiles is 20 times more powerful than the bomb dropped on Hiroshima and could kill millions if dropped on a major city. The Air Force still keeps nearly all 450 of them on constant alert, ready to go. We thought the missiles would be hidden away on some vast tract of federal land.
Lesley Stahl: My goodness, is this a farm right here?
Carl Jones: It is.
We were surprised the missiles were close to rural communities. We saw bales of hay and herds of grazing cattle.
Carl Jones: It's a safe weapon. I mean, it's not gonna do anything here on the ground.
Lesley Stahl: If by accident or a deliberate act, one of those missiles was launched, is there a way to disarm it or bring it back?
Carl Jones: No, we can only launch with direction from the president of the United States. Now once that missile has gone, there's no way to recall it or disarm the warhead that's on the missile. Once they're gone. They're gone.
The missiles are spread out over a wide area surrounding three Air Force bases in five different states. A web of underground hardened and pressurized cables connect the missiles to buildings like this -- where the missiles are monitored remotely miles away in capsules 70 feet underground.
The control rooms hang on shock-absorbers within a protective shell of concrete and steel. The system was designed in another era, the 1960s, to survive a nuclear blast.
We went down by elevator and were escorted to a door that weighs eight tons.
Chaz Demerath: ma'am and sir i would like to welcome you to...
We were allowed to go inside, provided we use an old, Air Force camera and let security officials vet this footage.
The so-called "missileers" who watch over and control the missiles work in teams of two, on 24-hour shifts known as "alerts." They have everything down here they need to survive. We expected to find pot-bellied veterans at the controls. Instead, we found Chaz Demerath who's 25, just three years out of the Air Force Academy. And his deputy, Dana Meyers, 23.
This was only her fifth time on duty. When they started their 24-hour shift, they took custody of 10 nuclear weapons.
Lesley Stahl: So I guess I have to ask you the inevitable question: where is the button?
Chaz Demerath: Where is the big button? Ma'am there is no button.
Lesley Stahl: There is no button?
Chaz Demerath: There is no button.
There are three switches and a key, which is kept in this strongbox with two locks on it. Demerath has one combination, Meyers has the other. It's one of many layers of safeguards built into the system.
Chaz Demerath: Even though we trust each other, we don't trust each other.
Lesley Stahl: Ah ha.
We thought the work would be tedious, just waiting for something that'll probably never happen - to happen. But from nearly the moment we asked the question...
Lesley Stahl: Is this just boring beyond belief?
Chaz Demerath: It is never boring because we have so many actions we do every day.
Alarms started beeping and the phones kept ringing.
Chaz Demerath: Ma'am, I mean to ask all of you to remove all yourselves from the capsule at this point.
Lesley Stahl: So is there anything wrong?
Chaz Demerath: Nothing wrong at this point.
We were politely asked to leave at least eight times -- so they could decode messages or deal with other classified information.
Lesley Stahl: OK, I'm back.
The officers may be young...
Chaz Demerath: If you can imagine that as being your computer...
But the equipment is ancient. This, for example, is one of the computers that would receive a launch order from the president. It uses floppy disks! The really old, big ones.
Lesley Stahl: Before you got down here you probably had never seen one of these?
Dana Meyers: I had never seen one of these until I got down in missiles.
The reason the Air Force allowed us to visit the missile fields surrounding Warren Air Force Base is because it wanted to counter all the bad press it's been getting lately at the two other bases that also guard our land-based missiles.
Last year, 17 missileers at Minot Air Force Base in North Dakota were removed from duty after performing poorly on an inspection. At Malmstrom Air Force Base in Montana, three missileers are under investigation for drug possession and 91 have been implicated in a scandal involving cheating on routine tests.
[Jack Weinstein: I am flying back...]
Maj. General Jack Weinstein took control of all three nuclear bases in December, with a mandate to find out what ails the missile corps and fix it.
Lesley Stahl: Let me ask you a question: whether there's, I guess you'd call it an identity crisis with the mission as a whole. You have these nuclear weapons that no one believes we'll ever use so do you find that that's an issue: the question of what's the mission?
Jack Weinstein: No, because we use these weapons every single day protecting our nation. Deterrence has a value. It has a value for our nation; it has a value for our allies.
Gen. Weinstein commands a force of 9,600 including maintenance technicians who keep the missiles in working order. Security forces that guard the weapons and provide a heavily-armed escort any time the warheads are being moved and about 500 missileers who man 45 control centers round the clock. The vast majority, the general says, have not cheated on tests.
Jack Weinstein: We're talking about one percent of the 9,600 people that work for me that did violate our core values.
Lesley Stahl: But when you say one percent, it's not one percent of the missileers, right? You're talking about everybody?
Jack Weinstein: Right.
Lesley Stahl: It's a much larger percent of the missileers?
Jack Weinstein: Right. It's about 20 percent of the missileers.
Lesley Stahl: Well, that's huge.
Jack Weinstein: It is huge. And that's why we've taken accountability for those people.
Gen. Weinstein also removed the directors of operation. On Gen. Weinstein's recommendation the Air Force brass announced that the Montana base commander would resign and that nine other officers under him would be removed. Weinstein told us investigators found no evidence of cheating at the two other missile bases. But that's not what our reporting found.
Lesley Stahl: You know it's interesting because we spoke to a lot of former missileers, and they just say cheating goes on everywhere and it's been going on for quite a long time.
Jack Weinstein: What we did was we look at the evidence. Whenever we saw a cell phone, whether it was a text message or an email, we investigated that.
Lesley Stahl: One of the people who told us about this cheating being endemic, was an instructor at this base who left last year.
Jack Weinstein: Well, I will tell you that as a commander, if I have any indication that people aren't following our core values, I immediately attack the problem. And we have not seen this problem at the other two bases.
The former missileers told us that the missile corps has long been treated like the step child of the Air Force. Pilots get all the glory; missileers have fewer chances for advancement.
[Teacher: We're going review the monthly lesson plan and then we're going to take a test.]
It's said that the reason for the cheating is a "culture of perfection" where missileers have felt they had to get 100 percent on the tests they take three times a month or face no chance of promotion. We spoke to a group of current missileers at Warren Air Force Base - including 26-year-old Daniel Sharp from Tennessee.
Lesley Stahl: Why did people feel they had to score 100 percent?
Daniel Sharp: When I first came here leadership that was in place told me that the minimum passing score for my test was a 90 percent, but if I was making 90s I was a D student. And I would be treated that way.
Lesley Stahl: But you actually were here under that 100 percent pressure yourself.
Daniel Sharp: I was.
Lesley Stahl: And you felt the pressure and that caused stress, I'm sure of it.
Daniel Sharp: Absolutely. But it also caused a great deal of studying and a great deal of proficiency.
Jack Weinstein: No one cheated because they had to-- they didn't know the material. They cheated in order to get 100.
Lesley Stahl: Is that gone?
Jack Weinstein: That's gone.
Lesley Stahl: So what replaces that?
Jack Weinstein: Well, right now, it's pass-fail. As long as they get, you know, above the 90, which is the standard--
Lesley Stahl: Wait, wait, wait. Pass-- it's still pass-- you fail at 90?
Jack Weinstein: Yeah, it's still at 90 right now.
Lesley Stahl: Wow. How is that improving things?
Jack Weinstein: When you take away the pressure of getting 100 on a test, you have people, focused on what they need to know. I think it changes things.
It's one of a number of things the general's doing to boost morale, which by most accounts has been low for a long time, even at the top. Last year, Weinstein's predecessor, Maj. General Michael Carey, was relieved of command for drunken and inappropriate behavior during an official trip to Moscow. According to an Inspector General's report, Carey complained that his troops had "the worst morale of any airmen in the Air Force."
Lesley Stahl: How many of you chose to be a missileer as your first choice for your military career? Two of you.
Truth be told, the vast majority don't choose this job. This group was impressive. They majored in physics, engineering, and English, and many are working on their advanced degrees.
Lesley Stahl: We've obviously heard a lot about the morale problems. So I wonder what the morale problems come from.
Clair Reynolds: Well, it fluctuates. And there are times where it just becomes a grind because you're doing so much in a short period of time, a lot of times. And you just have to adapt and work with the schedule you're given.
Lesley Stahl: So it can be more than 24 hours?
Jennifer Leute: Of course, weather does impact how long we might be downstairs. If we have poor weather, especially during the winter, we do get that a lot in these northern bases, you might be down there for 48 hours at a time or possibly 72.
Lesley Stahl: Anybody been down for 72? No? 48?
Various: Yes. Yeah.
Lesley Stahl: 48, a lot of you.
They told us they feel things are improving and they also assured us there are many safeguards built into the systems of the launch control centers - or "LCCs" - to prevent an unauthorized launch.
Lesley Stahl: Are any of you partners?
Daniel Sharp: Yes, ma'am. Lieutenant Matuu and I.
Lesley Stahl: You're partners. OK. Just for the sake of this discussion, let's say both of you go bonkers. And you get the key out and you do-- you switch it on. Will it go off?
Daniel Sharp: No, ma'am.
Melissa Matuu: No.
Lesley Stahl: It won't go off? Why not?
Melissa Matuu: 'Cause there are enable codes that we need in order to get the missile ready for launching.
Brandon Castillo: Only the president of the United States could authorize a launch of nuclear weapons.
Daniel Sharp: And one capsule by themselves can't do it alone.
Brandon Castillo: Right.
Lesley Stahl: You would have to receive the codes to put them in? You don't have them when you go into the LCC?
Daniel Sharp: No, ma'am.
Lesley Stahl: OK, well, that's reassuring.
An important part of their job is monitoring the condition of the missiles. If they get a signal that something's wrong, they ask for a maintenance crew to fix it.
Lesley Stahl: Oh wow.
The maintenance crews train on this missile that is virtually identical to the real thing minus the rocket fuel and warhead.
The systems are so complex, the technicians work off detailed checklists.
They're constantly shouting "two-two," because the rules require there always be two people keeping an eye on one another when they work on a nuclear missile. The idea is to ensure safety and prevent sabotage. Sometimes these Minutemen-3s have to be removed from their silos for repairs or for random test-launches -- without the warhead, of course -- to make sure the missiles still work.
These missiles were designed and built during the Cold War when there was always the fear of a nuclear attack from the Soviet Union. But the second in command of all U.S. nuclear forces said recently that he's more concerned about an accident or human error than a Russian attack.
When we come back, we'll tell you about some mishaps in the past that nearly led to accidental nuclear detonations on U.S. soil.
For more than 50 years, land-based nuclear missiles and long-range bombers have played a key role in America's strategy to deter other nations from using their nuclear weapons against us.
But the age of the equipment is a problem, and human error is always a concern. Small mistakes -- like a dropped socket -- can mean the difference between routine maintenance and a major accident.
We were not aware until we started researching this story how many close calls there have been involving nuclear weapons: fires, plane crashes, fuel explosions, even a bomb that was accidentally dropped on U.S. soil. The seriousness of many of these incidents was not disclosed at the time. But, as Lesley Stahl reported in April, witness accounts and declassified government documents, we have a much better understanding today of how close we have come to a nuclear disaster.
Eric Schlosser: We came close on numerous occasions during the Cold War to having our own weapons detonate accidentally on American soil.
Eric Schlosser spent six years investigating nuclear weapons mishaps during the Cold War. His book, "Command and Control," describes a number of hair-raising incidents.
Like a rocket fuel explosion in 1980 in Damascus, Ark., that forced the evacuation of people living near a Titan II missile complex.
Eric Schlosser: Someone dropped a socket in the silo. And the socket fell about 70 feet, pierced the missile, caused a fuel leak and then there was a huge explosion.
Lesley Stahl: If that exploded, how come no-- you say there was no detonation?
Eric Schlosser: They put safety mechanisms in the warheads to make sure they only detonate over the target where they're supposed to. And that's a testament to the engineering skill of the warhead designers and to good luck.
Schlosser says that's not the only time we were lucky. A few days after John Kennedy's inauguration in 1961, an Air Force B-52 like this one had mechanical problems and accidentally dropped a nuclear bomb over Goldsboro,N.C.
Eric Schlosser: When it hit the ground, the firing signal was sent. But one safety switch prevented a full-scale detonation of a powerful hydrogen bomb in North Carolina.
Lesley Stahl: OK, I'm kind of shocked cause I didn't hear that story ever, did I? Until you revealed it?
Eric Schlosser: Well...
Lesley Stahl: Was that made public?
Eric Schlosser: There was a real effort throughout the Cold War to deny that there was any possibility that a nuclear weapon could detonate by accident.
Today's Minuteman 3 missiles use rocket fuel that's more stable and less likely to explode. And they've upgraded some key components too, like the guidance systems that direct the missiles toward their target.
Eric Schlosser: The nuclear weapons themselves, the warhead, the bombs, are much safer than they were 30 years ago. There's no question about that. But the infrastructure, the equipment what carries those weapons...
Lesley Stahl: The Minuteman itself goes back--
Eric Schlosser:: To the Nixon administration.
Lesley Stahl: The Nixon administration.
Eric Schlosser: Look at it this way. If you got a beautiful sports car from the 1960s, it would drive really fast and it would be fun to drive, but a modern car is gonna have so many more safety mechanisms that are so much more sophisticated. And the architecture, the command and control architecture is complicated and aging.
Lesley Stahl: How would you evaluate the risk of an accident happening, a human error kind of thing?
Jack Weistein: The probability is as close to zero as you can get--
Major General Jack Weistein's first job as a young airman was manning one of those launch control centers. Today he's in charge of all 450 land-based intercontinental ballistic missiles in the U.S.
Lesley Stahl: You have said that you sleep well at night.
Jack Weistein: That's a direct quote.
Lesley Stahl: Some people would say you shouldn't be sleeping well at night. You should be constantly worried because you have a very complex system here. And there are a lotta things that could go wrong.
Jack Weinstein: The people that designed this weapon system in the 1960s, even though we've made upgrades, are actually brilliant. And there's a lotta safety mechanisms built into the system.
But during our visit to the underground control center with Colonel Carl Jones, we got a glimpse of what the missile corps is up against. Take this enormous outer door designed to protect the corridor leading to the capsule. They can't close it because of a broken part, so it's propped open with a crowbar and marked with a danger tag. We were told the door has been disabled like this for years.
Carl Jones: Many things in the capsule, in the equipment building, aren't manufactured anymore. So we have to figure out a way to manufacture that piece, and see if the new piece will work.
At a missile silo we visited, time and frigid weather had clearly taken their toll. The missile was being pulled from the silo for repairs because water had seeped in.
[Martin: It's probably the worst case of loose nukes in U.S. military history.]
Some nuclear weapons snafus have happened fairly recently. In 2007, six nuclear-tipped cruise missiles were loaded onto a B-52 by mistake, flown across the country, and left unguarded on the tarmac. No one noticed for 36 hours. That led then-Defense Secretary Robert Gates to ask the Air Force secretary and chief of staff to resign.
In 2010, because of a technical glitch, a missile squadron at the base we visited in Wyoming stopped receiving electronic messages from the missiles it was charged with monitoring.
Jack Weinstein: What happened was we lost status monitoring of 50 missiles. What we-
Lesley Stahl: Fifty missiles?
Jack Weinstein: Fifty, it was a squadron. What we--
Lesley Stahl: For an hour?
Jack Weinstein: A little under an hour, but an hour.
Lesley Stahl: What word would you use to describe that? Is it serious? Was it dangerous?
Jack Weinstein: I don't view it as dangerous at all because of the safety of the weapon system. I would call it serious when you lose status monitoring for that period of time.
Being able to communicate - with the missiles and with others on the base - is essential to a missileer's job. So we were surprised to learn they were having trouble hearing what was being said on their phones.
[Dana Meyers: Can you repeat that?]
Lesley Stahl: What about the phones?
Jennifer Leute: They're awful.
Claire Reynolds: Yeah, they're-- they're not so great.
Lesley Stahl: What isn't great about them? The-- is it-- what--
Melissa Matuu: Just the connection.
Lesley Stahl: The hearing or is it that you can't connect when you make a call or?
Jennifer Leute: It's both. I mean, you can't hear the other person on the other end of the line. Sometimes you can't dial out, which makes it very difficult if you're trying to do your job.
Just to be clear: the president will not be calling them on the phone with his launch orders. They have other more secure systems for that. But still--
Jack Weinstein: It is an analog system. And when you have an analog system, there are problems. We're looking at upgrading that in the next few years.
Lesley Stahl: Years.
Jack Weinstein: Next few years.
Lesley Stahl: Not months?
Jack Weinstein: No, years.
Lesley Stahl: And they're using really, really, really old computers. I saw a floppy disc and not a floppy disc that size. It was gigantic.
Lesley Stahl: Now, explain that.
Jack Weinstein: A few years ago we did a complete analysis of our entire network. Cyber engineers found out that the system is extremely safe and extremely secure on the way it's developed.
Lesley Stahl: Meaning that you're not up on the Internet kind of thing?
Jack Weinstein: We're not up on the Internet.
Lesley Stahl: So did the cyber people recommend you keep it the way it is?
Jack Weinstein: For right now, yes.
A terrorist attack is also a major concern. This tactical security team trains constantly to take back a missile silo from the bad guys if they ever get in. Once the team enters the compound and secures the site, they go down into the silo fast-roping and drawing their guns quicker than most of us can tie a shoelace.
The land-based intercontinental ballistic missiles, the ICBMs, that we saw are just one part of the nuclear triad that includes missiles on submarines and bombers. The Congressional Budget Office estimates that operating and upgrading all three legs of the triad is going to cost at least $355 billion over the next 10 years.
Lesley Stahl: Do we need all three legs of the triad?
Eric Schlosser: I think that the one leg of the triad that may be the least useful are our missiles.
Lesley Stahl: The land-based.
Eric Schlosser: The land-based missiles are targets. The Russians know exactly where they are. It puts the states where they are based at risk whereas with submarines, they're hidden. One of the things about a bomber is if the bomber takes off with nuclear weapons, and you change your mind, you can have the bomber come back to the base. And you can't do that with a land-based missile.
Lesley Stahl: The land-based leg of the triad, do we need to have that?
Jack Weinstein: I think it's extremely important to have an on-alert, 24/7 nuclear capability to protect our nation when, I think, we need to look at the problem set sometimes in the eyes of other nations. When other nations are upgrading their ICBM force, they're modernizing their ICBM force, I think it's extremely important that we provide the American public with that day-to-day deterrent value that the ICBM provides.
Lesley Stahl: And that's the mission.
Jack Weinstein: And that's the mission.
We were watching the missileers practicing their procedures in a simulator.
Kristen: Would you like to do a key turn?
When one of the instructors offered us a chance to do a practice launch, it was simple enough to turn the switches.
Kristen: And in 3, 2, 1 turn.
Lesley Stahl: How many missiles did I actually launch? One or 10?
Kristen: You launched 50.
Lesley Stahl: I launched 50?
Daniel Sharp: I would say everybody here would remember their first alert. You ride the elevator down, you go through those first two massive blast doors and you're looking at the same console you've been training on for so long. But this one is tethered directly to 10 nuclear weapons with status monitoring for an additional 40. And that weighs on you, absolutely weighs on you.
We left the base more aware of the pressures these young officers are under - and hoping their superiors will get around to fixing those phones and broken doors.
The Air Force tells us it plans to spend nearly a billion dollars over the next six years to upgrade those launch control centers and missile silos and make other improvements to its nuclear force. The spending will require congressional approval.