Nuclear weapons have only been used twice in warfare. TWICE. Both in 1945. Both by the Yanks.
There have been thousands of 'tests' in the following 79 years, but none fired 'in anger'.
It's all sabre rattling.
If (and it's a very big if) WW3 breaks out in the near future, the most likely battleground will be the Middle East or, at worst, Eastern Europe.
It will involve troops on the ground, and without conscription, our (UK) forces will form a relatively small part of a larger European force.
In the event of conscription being introduced in the UK, there will probably be massive breakouts of conscientious objection and pacifism by young males across Britain. Indeed, there's likely to be a far greater number of 60+ volunteers than 18-45 conscripts.
It won't happen.
If Russia had the will to attack the West, they'd have done it years ago. Putin isn't stupid, neither are those around him. They could cut off gas, oil etc, and Western Europe would be on it's knees within 3 months. They only have to threaten such action and Western Europe will come to a peaceful, diplomatic settlement before you know it.
If China want to take over the world, they will do it economically. They'll be the next World leader in the financial market. It's cyclical. It's their turn next, and they know it.
As always, it's going to be down to the yanks as to how this plays out. They've got a piss poor record when it comes to armed conflict, and their people don't have the appetite for it.
Nobody wants a major war. It's in nobody's interests. It won't happen.
Just my opinion.
