The BBC had a story this morning that got my attention and unless you're a really early riser, and NPR listener you most likely missed it. We tend to forget that the Brits have missile boats out there, though only four to our 14 Ohio Class Submarines. The US also has 4 Ohio class subs that have been converted to carry conventional warheads. Just the same one wrong move and BOOM! End of the world as we know it.
From the BBC's Richard Knight
One of Britain's four Trident submarines is always out there, somewhere under the Atlantic, carrying more destructive power than was unleashed in the entire campaign of World War II.
It moves through the deep: silent, undetectable, untouchable.
This is Britain's nuclear deterrent and the logic is simple: whatever happens to the mainland, even if it's utterly destroyed in a surprise attack, that lone submarine will always be ready and able to strike back with overwhelming force.
For a BBC Radio 4 documentary, The Human Button, we were given unprecedented access to Britain's nuclear weapons infrastructure in order to answer three basic questions: How does the system work? What's it like to be a part of it and is it fail-safe?
Safeguards are built into the system from top to bottom.
Two men (and so far they have always been men) are needed to authenticate each step of the process from the government emergency room somewhere under Whitehall, where the prime minister's decision to fire would most likely be taken.
It would be relayed to the CTF 345 bunker at the Northwood facility in Middlesex, through which the command is passed on to the submarine on patrol and to the missile control centre on board that submarine itself.
But what would happen if the prime minister requested a strike for which, in the minds of his advisors, there was no justification?
In other words, can the system protect against a PM who, in a period of rapidly escalating international tension, loses it?
Under our unwritten constitution that question has never been satisfactorily answered - until now.
Lord Guthrie, who as chief of the defence staff briefed the newly-elected Tony Blair on the system in 1997, says the ultimate fail-safe is the fact that the head of the armed services is not the prime minister, but the Queen.
"I think the chief of the defence staff, if he really did think the prime minister had gone mad, would make quite sure that that order was not obeyed.
"And I think you have to remember that actually prime ministers give direction, they tell the chief of the defence staff what they want, but it's not prime ministers who actually tell a sailor to press a button in the middle of the Atlantic.
"The armed forces are loyal, and we live in a democracy, but actually their ultimate authority is the Queen."
The prime minister can sack the chief of the defence staff. But only the Queen can approve the appointment of a new one. Is that the fail-safe?
"You could say that," says Guthrie.
"He might find a more pliable one, I suppose. I suspect during the time when he was hunting around for a new chief of the defence staff, common sense would prevail."
It's one thing for the chief of the defence staff to refuse to obey a prime ministerial instruction, but what if someone further down the firing chain felt they simply couldn't go through with it?
Toby Elliott was commander of the Polaris (the precursor to Trident) submarine HMS Resolution in the 1980s. He says he knew men who doubted their own resolve. They were, in effect, punished for it.
"I knew several of my colleagues who went through the commanding officers' course and who were then selected to command Polaris submarines who said they couldn't do it," says Elliott.
"They were very brave to do so. In some cases they lost their sea-going appointment and effectively ended their Naval careers."
Was that because there weren't other boats for them to command?
"No," says Elliott, "it was because they turned down the opportunity, or the invitation, to command a Polaris submarine - because they had doubts about their ability to carry out the ultimate act."
Commander Richard Lindsey is the captain of HMS Vanguard, the Trident submarine on patrol right now. He says his men would not be there if they couldn't go through with it.
"I'm sure that if somebody was on board who did not want to be here, they would have followed a process of leaving the submarine service or finding something else to do in the Navy," he says.
Doubts about the job, Lindsey explains, are more likely to focus on the rigours of the patrol.
"The doubt might not be placed just purely on the deterrent, the doubt can be placed in terms of the personal commitment by being away from home - the nil communication process.
Out of the armed forces, there are only going to be approximately 160 people who have no communication at all with their families."
Ultimately, the system - for all its complex mechanisms - relies on individuals to make it work.
Very few people in the history of the world have held anything like the degree of responsibility that those individuals hold.
The destructive power they could unleash, if called upon to do so, is unimaginable.
But be assured: the fail-safes are many and they are almost certainly fool-proof - even if the prime minister goes berserk.