because when you’re fighting with nukes there are no winners. Only a destroyed hellscape.

Checkout the super relevant movie Threads. Shows the horrors of nuclear holocaust in excruciating detail. It takes place in the UK but the situation would be the same anywhere nukes hit: complete and utter devastation for all.

If any nuclear attack would be met with a counter attack using nukes, the whole world would suffer from the fallout that wouldn't be contained only within the national boundaries of the countries that get nuked.

https://en.wikipedia.org/wiki/Nuclear_holocaust

Nukes are like Tik tac toe.

A strange game the only winning move is not to play.

M.A.D

Mutually Assured Destruction

During the Cuban middle crisis and around the time of Tsar Bomba people in the US had the capability to make 10 Gigaton Bombs.

It comes down to how you define winning. Define L(X_i) as the 'loss' of warring party i at the end of the war - positive loss means that party i is worse off at the end of the war, while negative loss means party i is better off at the end of the war. If you are playing a board game, the rules might say someone always wins, and it is party i with the lowest L(X_i). But in a real life war, if party 1 started the war, their objective is probably that L(X_1) < 0 - i.e. they started the war to profit, not just to lose less than other parties. So in a real war, it is fair to say a party i loses if L(X_i) > 0, and wins if L(X_i) < 0. So to say no-one wins a war with parties P is to say \forall_{i \elem P} L(x_i) < 0.

Now in the case of wide scale nuclear war, parties likely launch all their nukes at each other within minutes so they launch before their capability to launch is destroyed. All major cities in all parties will likely be destroyed, and contaminated with nuclear fallout that may take years to decay to safe levels. Particulate thrown up by explosions would likely block out the sun and spoil all agriculture on earth for years (nuclear winter). Most people on earth would die. Government and civilisation would be unlikely to be able to continue under such circumstances - people might at least fall back to tribal organisation for a while.

So a widescale nuclear war would almost certainly lead everyone with a positive loss function - hence 'no winners'.

because boom, boom, everyone dead?

Nuclear weapons spread vast quantities of highly toxic, highly radioactive dust in all directions, clean into the stratosphere.

Any significant use of these weapons would render the entire planet uninhabitable, and cause total catastrophic breakdown of every ecosystem. Even if you survived the direct attack, there would be no clean air, no clean water - and in a very short time, no plants or animals. The forests and oceans would die, there'd be nothing left to cycle CO2 back to oxygen, the ocean currents would be disrupted, rainfall patterns would be destroyed (even if they weren't coating everything in more radioactive dust), it would be impossible to grow food - the planet would simply stop sustaining life. And that's not even counting nuclear winter, an ice age brought on by the sheer quantity of stratospheric dust blocking out the sunlight (not dissimilar to the meteor wiping out the dinosaurs)

It's hard to cast yourself as a winner if you're shitting your intestines out from radiation poisoning, with no hope whatsoever of anyone at all getting through this.

It's called mutually assured destruction. 2 nuclear nations likely have the firepower to wipe each other off the face of the planet.

How can a country win when it no longer exists? It's very hard to stop a nuke that's been launched, and it takes an ICBM a couple hours to arrive after they've obviously been launched, at which a point the other guy fires back. Basically both sides of the exchange get hit hard, and have most of their cities and industrial capacity burned down with the people inside. And that's not even considering a possible nuclear winter, which modeling suggests would last a decade.

This is also why tech to block missiles is controversial. If you open up an even tenuous path to victory for one side the odds of a war starting get much higher.

one word (and a number): WarGames (1983)