MPs are set to decide on Monday (July 18) whether to renew the UK's controversial Trident nuclear deterrent.
We asked those in west London how they would be voting, and while the majority said they were in favour of replacing the defence system, one opponent described nuclear weapons as "immoral and illegal".
Trident, which consists of four submarines armed with nuclear warheads, is expected to reach the end of its working life at some point during the 2030s.
The government estimates it will cost £31 billion to replace the submarines and says sustaining the system currently accounts for around 6% of Britain's annual defence budget.
The Campaign for Nuclear Disarmament claims renewing Trident would cost at least £205bn over the 30-year lifespan of the new system.
The Treaty on the Non-Proliferation of Nuclear Weapons, signed by the UK, requires all parties to "pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament".
The government says that, as a recognised nuclear weapon state, maintaining and renewing elements of the UK's nuclear deterrent capability is in keeping with its obligations under the treaty.
Both the Conservatives and Labour said during the 2015 general election that they supported replacing Trident, but Labour leader Jeremy Corbyn favours nuclear disarmament.
So how are west London's MPs planning to vote, and why?
BOB BLACKMAN, MP for Harrow East, CONSERVATIVE
Mr Blackman voted in January 2015 and in November that year in favour of renewing Trident.
He was also one of 10 MPs to sign an early day motion in January 2016 calling on parliament to support the renewal of Britain's nuclear deterrent.
VICTORIA BORWICK, MP for Kensington, CONSERVATIVE
"Britain faces a number of serious threats on the international stage and our national security must address these," she told getwestlondon.
"The vote on Monday will determine the future of our national security and while it is important to listen to both sides of the argument, it is vital to consider the role a nuclear deterrent plays in Britain's security by ensuring we cannot be held to ransom by rogue states."
RUTH CADBURY, MP for Brentford and Isleworth, LABOUR
"I am a Quaker, and therefore I oppose the renewal of Trident. Nuclear weapons, as weapons of mass destruction, are immoral and illegal," she told getwestlondon.
"I believe we should be investing in peace building and peace keeping, not in machinery with the power to destroy our world many times over."
MARK FIELD, MP for the Cities of London and Westminster, CONSERVATIVE
Mr Field voted in favour of renewing Trident in January 2015 and November of that year, according to the website TheyWorkForYou.com.
GREG HANDS, MP for Chelsea and Fulham, CONSERVATIVE
"I will be voting on Monday in favour of renewing Britain's independent nuclear deterrent," he told getwestlondon.
"It's the right thing to do in a dangerous world with many known foes and the possibility of more in the future. Now is not the time to be taking a risk with Britain's defences."
BORIS JOHNSON, MP for Uxbridge and South Ruislip, CONSERVATIVE
Britain's newly-appointed foreign secretary has consistently spoken out in favour of renewing Trident.
In his Telegraph column last year he argued that to do otherwise would leave the country "vulnerable to nuclear blackmail" and send out a signal that it "no longer wished to be taken seriously".
SEEMA MALHOTRA, MP for Feltham and Heston, LABOUR
"At the election I was asked my view on Trident. I said I believed in multilateral disarmament," she told getwestlondon.
"I have discussed this with colleagues and constituents and recognise the different views on the issue.
"With the growing instability in the world we need to keep our defences strong. I have therefore reached the view that I will vote to support keeping a continuous at sea deterrent."
JOHN MCDONNELL, MP for Hayes and Harlington, LABOUR
"John is opposed to nuclear power and campaigns for the scrapping of Trident," his website states.
