The only thing on which I agreed with Stewart Malcolm McDonald was the tribute he took the trouble to pay at the beginning of his speech to the crews of the Polaris and Vanguard submarines. They have been the backbone of Operation Relentless, and the success of that operation is entirely dependent on the commitment of those who have conducted those patrols—in each case, an extraordinary service of perhaps three months or more.
There is no other service in the Navy quite like it, with submariners cut off from the outside world unlike in any part of the Royal Navy, unable to visit foreign ports or carry out different missions. They are isolated from their family and friends at all times in that three-month period. They are the stoics of the sea and we do owe them our gratitude. We should salute them all, past and present, and look again at how that service can be better recognised, but we should also tell them loudly from this House: thank you for helping keep us safe. They did keep us safe.
As my right hon. Friend Dr Lewis said, it is extraordinary that some still argue that the nuclear deterrent is never used. It is used every minute of every hour of every day to ensure uncertainty in the mind of any aggressor towards this country. While we have nuclear weapons, they can never be sure what our response is likely to be. He reminded us that that was endorsed by a majority of 355 as recently as three years ago when we authorised the replacement of the Vanguard boats by the new Dreadnought submarines.
The Prime Minister and I set out the arguments for that renewal three years ago. I will not repeat them, but I want to make three further points. The threats we identified then, back in July 2016, have increased. First, Russia not only has intensified its rhetoric but is modernising its nuclear forces. It now has the ability to station nuclear missiles in its exclave at Kaliningrad, or indeed in the territory it now controls in Crimea. Secondly, since that debate, North Korea has carried out nuclear tests and is developing systems whereby nuclear warheads can be launched from both space and submarines. We should never forget that London is as close to North Korea as is Los Angeles. Thirdly, nuclear material is now coming within reach of terrorist groups that wish us and others harm. Our response must be relentless and resolute.