In the plains of North Dakota, U.S. Air Force Major Kevin Johnston rode an elevator nearly six stories underground. The old machine creaked as it lowered and stopped with a shudder. The elevator opened to reveal an eight-ton concrete door designed to withstand a nuclear blast. Beyond the door was a small room, called a launch control center. This would be Johnston’s home for the next 24 hours.
On any given day, 90 missileers like Johnston make a similar journey. At 45 different locations spread across five states, pairs of missileers ride elevators 60 and sometimes 90 feet underground to relieve the pair working the previous shift. They then sign their names into a logbook and assume responsibility for a portion of the country’s 400 intercontinental ballistic missiles (ICBMs), each of which carries a nuclear warhead, either a W78, designed by Los Alamos National Laboratory, or a W87, designed by Lawrence Livermore National Laboratory.
By placing missileers in launch control centers, the underground rooms from which ICBMs can be launched, the United States is able to respond to an attack at any moment, 365 days a year. But because the nation has never launched an armed ICBM—and hopes never to do so—going on alert often means that missileers must find productive ways to pass time.
“There’s a lot of maintenance we regularly perform on every ICBM, so that takes up a portion of your on-alert shift,” says Johnston, currently the junior Air Force Fellow at Los Alamos National Laboratory. “There are exercises we run and daily actions we need to complete, but there’s often a lot of down time that we try to make the most of. I was working on my master’s degree, so I studied a lot.”
At Minot Air Force Base in North Dakota, where Johnston was stationed until 2015, missileers typically pull on-alert duty eight times a month. Most shifts are routine. But occasionally something happens that makes those 24 hours anything but boring. Johnston remembers one shift that took a strange turn after an alarm sounded.
“Each alarm has a different sound,” Johnston remembers. “This alarm indicated that something had jostled an ICBM in its silo.”
Only the best come north
Johnston attended the United States Air Force Academy and planned to become a pilot, but during his senior year he learned about an eyesight problem that made flying impossible. “Without knowing much about missileers, I made a last-minute career switch,” Johnston remembers. “But the more I got involved in the nuclear mission, the more excited I became to play a role in something so important.”
Johnston arrived in North Dakota by way of Vandenberg Air Force Base, located on the coast of sunny southern California. “The first month I lived in Minot, a blizzard dumped so much snow that by spring, the snowmelt caused the worst flood the town had seen since the 1960s,” he remembers. “It was a culture shock, for sure.”
Appropriately, a sign above Minot’s guard gate reads, “Only the best come north.”
Less than an hour from the U.S.-Canada border, the base occupies 5,000 acres of offices, family housing, airplane hangars, and runways. If the distant missile silos and launch control centers are included, Minot spreads across more than a half million acres of prairie.
Minot is the only Air Force base in the country with both a nuclear-capable bomber wing and a missileer wing. The 91st Missile Wing, where Johnston worked, oversees more than 150 Minuteman III ICBMs. The missile wings at F.E. Warren and Malmstrom Air Force bases in Wyoming and Montana, respectively, oversee additional ICBMs that are located in those two states plus Colorado and Nebraska. Altogether, the United States’ 400 ICBMs constitute the nation’s only ground-based nuclear deterrent.
First developed 60 years ago, the Minuteman III stands 60 feet tall and weighs more than 79,000 pounds. The missiles are kept in underground silos, but they have no trouble breaking free of their subterranean homes: in 180 seconds, an ICBM can reach 750 miles above Earth, where its expended rocket motors separate and fall back to Earth and its single nuclear warhead, tucked inside its reentry vehicle, continues on to a predetermined destination. From start to finish, a Minuteman III can deliver a nuclear attack to the other side of the world in fewer than 30 minutes.
The day had begun normally enough. On the morning of his shift, at 7 a.m., Johnston reported to a briefing room on base, where he and the other missileers reviewed the hand-over briefings, the notes that discussed scheduled ICBM maintenance, mission-related exercises, and security concerns from the previous shift.
After the meeting, Johnston and his partner drove across the plains to their appointed missile alert facility. “If you’ve ever watched the movie Fargo,” Johnston says, “the landscape looks pretty much like that—a whole lot of grass and not much else.”
Spread across the barren landscape are missile alert facilities that look like old warehouses. These facilities are the gateways to the launch control centers, which are linked to 10 ICBMs via computers and from which ICBMs can be launched.
“As missileers, we may be the people sitting underground behind launch control,” Johnston says. “But it’s a team effort to maintain a secure site and a secure nuclear deterrent. Every time you go on alert, you become very aware of how many people are behind the mission.”
Approximately 1,800 members of the 91st Missile Wing work together to ensure that the ICBMs at Minot are ready to launch at a moment’s notice. There’s the 91st Missile Maintenance Group, which runs diagnostics on the weapons and fixes anything that needs fixing. There’s the 91st Security Forces Group, the armed guards who patrol the base, the silos, and who ensure no unauthorized personnel enter the missile alert facilities. And there are approximately 200 missileers like Johnston, 30 of whom are on alert every day in Minot’s 15 launch control centers.
Inside the missile alert facility, Johnston and his partner checked in at the guard office and chatted with the security force team. They stepped into the elevator and rode down. At the bottom of the elevator shaft, the eight-ton blast door appeared. Like the door to a bank vault but bigger, this particular blast door was painted with a fire-breathing dragon guarding a castle, an ICBM in place of a turret.
Standing in front of the door, Johnston held a phone to his ear that buzzed the on-duty missileers on the other side of it. The door swung open. Before the on-duty team left, Johnston and his partner signed the logbook. They’d now taken custody of 10 ICBMs.
The room where the missileers spend the day on alert is about 10 feet wide and 20 feet long, shaped like a pill. In one corner is a bed where the two missileers can alternate catching some shut eye during shifts. There’s a toilet in another corner, racks of electrical equipment, and the launch control console—a metal unit the size of a credenza covered in knobs, keyboards, and monitors.
As Johnston settled in for a long day, the room wobbled ever so slightly. The launch control center is completely suspended to minimize shaking if an enemy’s nuclear weapon were to strike the ground above. “Technically, in the event of an attack, there’s an escape route from the launch control center,” Johnston explains. “But there’s little chance of us being able to leave the room after taking a direct nuclear hit. That’s what you sign up for when you become a missileer.”
In a scenario like that, Johnston and his partner would receive orders from the U.S. president on how to respond. The president might order an ICBM strike, in which case the missileers on alert would quickly review the classified launch codes to ensure the legitimacy of the order, flip a series of switches, and one missileer would insert a key in the computer frame, arming and firing an ICBM at a preordained target.
Don’t be alarmed
For the first half of Johnston’s shift that day, everything was normal. He and his partner ran a systems test that guaranteed the computer and ICBM were in working order; they ran through the preventive maintenance checklist. Johnston opened a book to study for his master’s degree, when an alarm beeped.
Alarms can go off when a silo door opens, if equipment on an ICBM fails, or if someone passes beyond a fence line in restricted areas. During a 24-hour shift, it’s not unusual for an alarm to sound, or even several alarms, and in most cases the cause is an animal—usually a rabbit—that tripped a motion sensor.
“We take the security of our ICBMs very seriously,” Johnston says. “Even if we know wildlife most likely triggered the alarm, we still send a guard out to check. It may be a false alarm 1,000 times in a row, but we have to be prepared for any possibility.”
The alarm that day was triggered by a gyroscope inside a missile. Gyroscopes—devices used for measuring or maintaining spatial orientation and angular velocity—are part of the Minuteman III’s internal guidance system, which was designed decades ago by Boeing Company. The system does not use GPS; instead, the missile relies on inertial navigation, a series of complex accelerators and hypersensitive gyroscopes that relay to the ICBM its speed and position and guide the missile to its target. The guidance system steers the missile through the atmosphere and beyond the bounds of Earth orbit, about twice as high as the International Space Station. Once the ICBM reaches a predetermined point in space, it releases its reentry vehicle with its nuclear warhead onboard.
“I was taught to visualize a virtual tunnel in the sky,” Johnston says. “The inertial guidance set flies the missile through that virtual tunnel to hit a specific window in space at a precise speed. Once the ICBM reaches that point, it releases the reentry vehicle, and the warhead follows a ballistic trajectory the rest of the way. It’s similar to throwing a football, except instead of being launched by your arm, it’s launched by a rocket.”
As Johnston looked at the computer monitor, he noticed that another gyroscope had registered an alarm, then another, and another, until all 10 gyroscopes on all 10 ICBMs in his control had alarmed.
Johnston didn’t understand what was happening. He knew that ICBMs must be ready to launch at any minute, so gyroscopes are always active, spinning even as they rest in the silos. Sometimes gyroscopes fail due to regular wear and tear, in which case they’re quickly replaced. But this was no mechanical failure.
Johnston again turned to his checklist, a booklet that contains a list of possible error messages and explanations of how to fix these errors. As he flipped the pages, he remembered something he’d heard in training.
“I remembered a scenario that had been brought up about earthquakes,” Johnston says, “about how the gyroscopes are so sensitive that they can register tremors from far away. But it’s one thing when you see this described in a slideshow, and it’s another thing when a bunch of silos start throwing gyroscope fault codes all at the same time.”
Johnston reported the sensor alert to the 91st Security Forces Group. He also radioed the 91st Missile Maintenance Group. Everyone snapped into action. After a quick systems test, the alarm stopped, and everything looked normal. “There was never any danger,” Johnston says, “but at that point I hadn’t experienced anything similar.”
A little later, Johnson turned on a television in the launch control center. Sure enough, there’d been an earthquake—on the other side of the world. “It reminded me how much design and engineering it took to create these missiles—to be durable enough to fly to outer space, then precisely drop a warhead onto a target, but sensitive enough to register an earthquake on another continent,” Johnston says. “To me, these missiles are a technological marvel.”
Hours later, Johnston repeated the day’s events in reverse: he welcomed the two missileers who reported for the next shift, and he watched as they signed the logbook and assumed control of the ICBMs. He rode the elevator up to the surface, then drove across the plains to base and, a bit later, to his house, where his wife, newborn daughter, and two dogs were waiting. Johnston’s day on alert was over, but for 90 other missileers, their shifts had just begun. ★