The Economist gives a more nuanced view [1]. Essentially saying the deterrent is independent and if support was pulled by the US that there wouldn’t be a ‘cliff edge’, which would potentially give time to replace.

The UK has produced its own nuclear weapons in the past and has weapons grade processing at Sellafield. There’s ~140 metric tons of separated plutonium stored there.

It is apparently enough material to build tens of thousands of nuclear weapons. Not every warhead has to be a billion megatons to be a deterrent.

[1] https://archive.is/Qz2lI

Trident is made by Lockheed Martin, though. Or does the UK have the capacity to perform maintenance and manufacture make spare parts on their own?

I guess there would be enough time to switch to French rockets even in the worst case.

> Trident is made by Lockheed Martin, though. Or does the UK have the capacity to perform maintenance and manufacture make spare parts on their own?

The Economist piece spells out that, yes, long term maintenance is problematic, but in the short term nothing will break over night.

With Polaris (the system before Trident) the UK was manufacturing the missiles (effectively under license). It seems unclear whether there's any similar arrangement with Trident.

I guess my main point was that the deterrent is independent (the UK prime minister decides when to fire and can do so without the US sign-off) and there's no cliff-edge where the tech can be disabled by the US. So, with the raw materials ready to go and UK arms manufacturers like BAE Systems perfectly capable of building the tech, the risk to the UK (of being without a nuclear deterrent) is relatively low. Not zero, but low.