Sincere question because I have no idea - is this a formal agreement? Do they pay for any of it? By this logic, given that we're part of NATO and so are the US, do we not share theirs?
Its part of their NATO membership.
I would imagine they get that right as part of the fact that they would be staging point for any NATO land operations against the former USSR.
I also cant remember if this is something I've said on here in the past or not so bear with me:
The reason there is no will to really give up the NATO nuclear deterrent is quite simple and it stems right the back to the start of the cold war.
NATO believed it could not win a conventional war against the former USSR, it was that cut and dry, the USSR had SO many troops, and SO much hardware that the NATO forces in Europe couldn't kill enough enough of them quickly enough to stop any concerted effort by the USSR to move into western Europe, a conventional war would be over before you know it NATO resistance would be utterly crushed in days.
The only realistic option to stop them would be the threat of nuclear weapons which is why there is no rush to get rid of them.
People still fear the old USSR, they fear the arab nations developing a meaningful nuclear arsenal, there really isnt an option to sit round the table and all be friends unfortunately.
My father used to fly vulcans back in the 60s and 70s when they were the nuclear deterrent, and he has some stories to tell about just how bad things were, for real.
He used to get scrambled at random times during the day or night, loaded with live ordinance waiting for the order to attack his target in the USSR. Which back then, was a one way mission, the Vulcan couldnt carry enough fuel for the return trip, and IF he made it to the target and got out, there would be nobody left to come back to.
His orders were to head to Cypress and if that was gone, to attempt to ditch in the sea and take it from there.
Nasty stuff all round really.