Nuclear weapons provide the human race with terrible power to wipe out whole cities, killing millions. Nuclear weapons are too powerful to be controlled by any single state or military alliance. Instead an international court should hold nuclear weapons.
The terrible power of nuclear weapons requires a guarantee that prevents them from being used, but that power should not be that of a single state. Only the court with due legal process should be able to authorise their use and never as a first strike. However, any regime that fired nuclear weapons could expect that it could be subjecting itself and its citizens to the same fate. While I hope that retribution would never be necessary, it is a terrible deterrent. Even so, the aim would be to bring those who ordered the firing of the weapons to justice rather than killing innocent civilians. With the threat of an impending nuclear strike hopefully people would surrender the criminals to an international court, and accept the sanction of the court. Which might be to provide land and support to the people devastated by a nuclear strike.
My understanding is that the Trident replacement would essentially still be an American weapon, and from a practical perspective we cannot guarantee that in the future we will always be able to trust America.
We need to start working with other countries who believe in international legality to set up an international court that would police the world stage. While many nations would initially resist this, it could make nation states holding their own nuclear weapons obsolete. The way to move to peace is to guarantee international law and justice. When the police were initially introduced in Britain they were hated and rejected, but they have come to be accepted. We need international policing.
If countries were prepared to work together then the cost of the nuclear deterrent could also be shared. Britain does not require an individual deterrent, it requires international cooperation, and should work urgently to this end. I am not proposing immediate disarmament, but instead working for international guarantees backed by intentional courts with international weapons for international peace.
I believe this is a sensible and caring response. I would like to be able to completely remove nuclear weapons however it is not that simple.