What is the likelihood of a nuclear war?

My take on a question asked on Quora.

Nuclear warfare, rule #1: nuclear weapons are terribly expensive.

It cost a fuckload of money to buy them and it also cost a fuckload of money to maintain them — and the more nuclear weapons you have, of course, the more it costs. For instance, most nuclear warheads need 4-5 grams of tritium and, since the tritium content of the reservoir is depleted at a yearly rate of 5.5% it must be replenished. One gram of tritium is often reported to costs about $30’000. Think about the state of the Russian economy, the effect of sanctions, what we have observed on their conventional weapons and, perhaps most importantly, the endemic corruption of their military. Is there any tritium left in their nuclear warheads?

Nuclear warfare, rule #2: there is no such thing as limited nuclear war.

If you shoot first, the only likely outcome is a massive retaliatory strike. Putin knows it and every member of the Russian nuclear chain of command knows it. Should they shoot, Russia will cease to exist within minutes. So it’s basically suicide. Sure, Russia maybe has enough functioning missiles and nuclear warheads to inflict intolerable casualties on its targets. But using nuke, especially against a NATO member country, is just like pointing a gun to your head and pulling the trigger — except you don’t just kill yourself, but millions of your own citizens. It’s pure madness but, yes, Putin could go completely insane. Which leads us to:

Nuclear warfare, rule #3: there is no such thing as a nuclear button.

The big red button only exists in bad movies. Nobody is stupid enough to create such a shooting system. We don’t know what the actual procedures are, but we know for sure that they are all very highly secure. We don’t know how many people would be involved in the process but, if Putin orders a nuclear strike, at least one other guy will have to obey that order for the strike to be effective. Will he? Moreover, it is very likely that at least some of Putin's closest associates will be aware of the decision. How will they react? Will they just wait quietly for their own total annihilation? Will they try to flee, knowing we’ll get them soon or later? Or will they try something to stop Putin?

Does that mean the risk is zero? Of course not. Putin might develop suicidal tendencies, his entourage might prefer a nuclear apocalypse to a trial at the International Court of Justice, the guys in the nuclear chain of command might be fanatics, and some of the missiles might fly, hit their target and explode as expected. The probability is ridiculously low but it is not zero.

Now consider the alternative. What will most likely happen if we let Putin do? What will he do if we agree to give in to his blackmail? What kind of message are we sending to all warmongering authoritarian dictators? What kind of world will we been living in when this kind of peoples take it for granted that using nuclear weapons to force us into submission works?

Putin wants us to be afraid but the reality is that, behind his impenetrable mask of emotionless machine, he is more afraid than we are.