Cutting down on nuclear armament, which I presume is what you are calling out Corbyn for, is hardly something that no one could reasonably consider. You realize there are entire countries without nuclear weapons, right?
Exactly, nobody questions whether other European nations (aside from France) don't care about security.
Furthermore, if Britain did give up Trident they wouldn't be the first nuclear power to give up on nuclear weapons, South Africa did it first.
I'd suggest Japan has the right idea with regards to nuclear weapons... retain the knowledge about how to build nuclear weapons, but don't retain an active stockpile you're not going to use.
Yes we can't operate and maintain (mostly maintain) without US assistance because we have made a plan where we share that duty. If we changed our minds and decided to go alone we would could do so.
The nukes on the subs can be launched without US approval. As members of NATO we would discuss before firing under most circumstances, but that is a rather different scenario to the "UK requires US authorisation to fire nukes" being implied elsewhere.
When it comes down to brass tacks we have complete operational control of our nukes independently. That in most situations we would discuss with our allies before nuking someone does not mean our nukes are not independent, nor does that we reduce costs by sharing maintenance of nukes not in our subs with the US mean we have lost independence.
So the argument that we do not have independent control of our nukes fails.
That is a short post and doesn't make a strong argument compared to the UK's House of Commons Defence Committee saying that the UK could not maintain and operate Trident independently.
Even if the UK could theoretically launch Trident without US authorisation, they wouldn't in practice.
What would Ukraine do with nukes? Threaten to nuke Moscow? Knowing their country would become radioactive glass in response? Russia would have no reason to assume Ukraine would be insane enough to use them over losing a few regions, and so would have no reason to take them much into account.
As a side note, Ukraine actually did have nuclear weapons post-USSR. Then, Ukraine agreed to give them up, in exchange for clauses in treaties where Russia guarantees its territorial integrity.
So now, after Crimean acquisition, we know that the Russian signature in nuclear treaties is worth nothing.
Ukraine is not part of NATO the UK is this makes a difference to our defence requirements. NATO might be stronger if the UK took half the money to be spent on Trident and spent it on fighter jets (and the other half on not cutting junior doctors' salaries or cutting taxes or whatever).
