If the unthinkable happens and a nuclear exchange between the US and North Korea or Russia happens, President Donald Trump will rely on a secure underground facility at a base in the middle of the United States to carry out his orders.
And four-star Air Force Gen. John Hyten, the commander of US Strategic Command, would be at the center of it all.
"Our strategic responses are always ready to respond and everybody should know that," Hyten told CNN in an interview inside the highly secured 'Battle Deck' where he would oversee a nuclear response if the US is attacked or if Trump decides to launch a pre-emptive strike. "That they are ready this minute -- under the ground, under the sea, in the air, we are ready to respond, and the adversaries of the world -- including Kim Jong Un -- have to know that."
Hyten spoke earlier this month as CNN was granted exclusive access to Strategic Command headquarters at Offutt Air Force Base in eastern Nebraska.
Hyten, who is in charge of the US nuclear arsenal, oversees a command of more than 184,000 military and civilian personnel -- all tasked with being on alert 24 hours a day, seven days a week in case of a ballistic missile attack on the US.
If that moment arrives, Hyten has to be ready to move into action immediately.
"I have six computer screens in my office; they all go off," Hyten said. "There is a verbal alarm that goes off, there is people telling me, there are about 10 different ways to make sure the commander knows that it is time to move."
Keeping a constant eye around the globe
Before it gets to that point, the Global Operations Center, a highly secured facility buried many stories underground, is keeping a constant eye around the globe for missile launches and assessing whether they pose any threat to US territory.
Whether it is another missile launch in North Korea or just the launching of a satellite somewhere in the world, the staff of this facility, led by a battle watch commander and a strike adviser, reacts quickly to launches on a nearly daily basis to determine whether Hyten, and anyone above him all the way up to the President, needs to be informed.
While the facility was rendered unclassified for the brief time CNN was there, normal operations were running concurrently at a separate location nearby in order to maintain the security level required to carry out the mission of Strategic Command.
And when the operations center sounded an alarm upon picking up signals of what were likely Russian missiles fired into Syria, the CNN team was immediately hustled out of the room while a launch assessment was made.
Every time the alarm sounds, highly classified data detailing the threat is instantly sent to Hyten. In a real world emergency, Battle Watch Commander Col. Carolyn Bird and her staff in the operations center can get anyone from the secretary of defense to the President on the phone if needed.
"There is nobody we can't get ahold of," Bird said, adding that it would take only a short amount of time to determine if there was a real threat to the United States or its allies.
And Hyten can rapidly brief the President on what is happening after rushing from his office to his command post.
"The pictures that we see on the screen will tell me exactly where the missile is, how high it is going, where the impact point is -- all of those things happen in a small number of minutes," Hyten said.
If a missile is headed for the US, a secured black safe in the operations center is opened that holds the nuclear decision handbook -- a complete duplicate of the nuclear launch options that are also contained in the bag that always accompanies the president -- euphemistically known as the "football."
"The president's football and our black book are duplicates," Bird said. "They contain the same information in the same way so that we are talking off the same documents when we are discussing nuclear options."
Bird and her strike adviser, Maj. Jared Dockendorf, who previously worked in missile silos that house US intercontinental ballistic missiles, are both extremely familiar with what is in the book.
"I study that on a daily basis and we also do training on a daily basis to refresh myself and the battle watch commander on what is in the black book," Dockendorf said.
While Bird could not divulge the contents of the book, she said it was a "thorough documentation of all of our options to present to the commander in chief," from Hyten, who would work with his staff to present the most relevant options in a real world event.
Hyten, who has spoken with Trump about the very high stakes involved, believes the President is ready for the ultimate test any commander in chief might face.
President Trump asks 'very hard questions'
"He asks me very hard questions. He wants to know exactly how it would work," Hyten said. "The employment of military force is always a difficult decision for any President and there is no more difficult decision than the employment of nuclear weapons. That's why he asks so many questions."
Hyten's role in a possible nuclear attack is so critical that Strategic Command maintains an aircraft on a nearby runway at the base for Hyten to be rushed to in order to carry out his mission, and advise the President on nuclear strike options from the air should the base itself come under attack.
With Trump set to meet North Korean Kim Jong Un in the coming months, Hyten said his preference is always for a diplomatic solution, but he always keeps his eyes wide open despite the fact the North's last missile launch occurred almost four months ago.
"I'm confident [Kim] did not stop building things when he stopped launching things," he said. "Now I can't go into the intelligence, but I have worked with rockets a long time. I know how long they take to build."
And it is not just the nuclear domain that Hyten oversees. Strategic Command has missions in the space and cyber realms as well.
"I believe the strength of the future is when we can figure out how to bring all of those capabilities to bear against an adversary, and all of those capabilities provide deterrence and keep an adversary from taking a misstep," Hyten said.
But he does spend a good amount of his time watching what Russia, China and other international actors say and do to develop their military capabilities and pushes to keep the United States ahead and ready for any eventuality.
"We have always been ahead of the world when it comes to those critical technologies, and we are today and everyone should know that," he said. "The question is 10 years from now will we still be ahead, and that's what I am concerned about."
In the end, though, Hyten's job is really about deterring any would-be adversary from deciding to launch an attack on the United States.
"If someone launches a nuclear weapon against us we launch one back," he said. "They launch another we launch another, they launch two and we launch two. You are on this escalation ladder that ends up nowhere. The key is to stop that behavior before it gets bad."