Have you ever leased a car? It's the same dynamic. Functionally it's yours right? Except that it's not, it belongs to the dealership and when the lease is over, it's either re-upped, bought or returned. You do the maintenance, you use it how you'd like (like buying groceries or vacationing), but the car isn't yours.
Same with the UK's Tridents.
They are leased to the UK, on a long-term lease agreement, but still leased and thus are still owned by the US, not the UK:
Following the acceleration of the U.S. Trident II D-5 programme, the existing Polaris Sales Agreement was modified in 1982 to permit the supply of the more advanced missiles. Under the agreement, the UK would lease 65 Trident II D-5 missiles from a larger pool of weapons based at Naval Submarine Base Kings Bay in the United States. The U.S. would maintain and support the missiles and the UK would manufacture its own submarines and warheads to go on the missiles.
The programme was projected to cost £5 billion, including the four submarines, the missiles, new facilities at Coulport and Faslane and a five per cent contribution to Trident II D-5 research and development. The option for a fifth submarine was discussed at the time but later discounted, and the number of missiles leased was later reduced from 65 to 58.
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As for why the need their own command and control structure, that was answered in my previous post. They are owned by the US, and leased to the UK, unless the US decides to cede operational control to the UK during a time of crisis or war. Same deal with B-61s in Turkey, and why Turkey can claim to posses nuclear weapons, which many Turks on PDF will claim.
At this point the agreement would no longer be controlling and the UK would have full custody. I should think they'd like to use the missiles that have now been ceded to them yes? They have their own command structure and target list for this reason. But until control is ceded by the US, they are US missiles being leased by the UK.
Counter how you want, I'm not arguing India's case, just the UK's and your claim that Trident violates both the NPT and MTCR.
If you'd like to offer India's views, I'm always willing to learn new things.
I didn't forget it, It just hadn't come up in our discussion. I'll cover it too if you'd like, and the justification for its sale.