The Labour leader Jeremy Corbyn has questioned the effectiveness of Trident, as MPs prepare to vote on renewal of Britain's nuclear deterrent.
Speaking in the Commons, he said: "What is the threat that we are facing that over a million people's deaths actually deters?
"It's not from the so-called Islamic State - their poisonous death cult glories in killing as many people as possible, as we've seen brutally in Syria, to east Africa, from France to Turkey.
"It hasn't deterred our ally, Saudi Arabia, from committing dreadful acts in the Yemen. It didn't stop Saddam Hussein's atrocities in the 1980s or the invasion of Kuwait in 1990. It didn't deter the war crimes in the Balkans in the 1990s, nor the genocide in Rwanda.
"I do not believe the threat of mass murder is a legitimate to go about dealing with international relations."
Theresa May accused Green MP Caroline Lucas and some Labour MPs of defending the country's enemies, as MPs prepare to vote on renewing Trident.
The MP for Brighton Pavilion had said the UK's nuclear weapons are "driving proliferation - not the opposite", before the prime minister rejected the suggestion, saying: "I have to say to you that sadly you and some members of the Labour Party seem to be the first to defend the country's enemies and the last to actually accept the capabilities that we need."
Mrs May said it is "a great pity" that members of the Labour front bench "fail to see the necessity" of Britain's nuclear deterrent "given that the Labour party in the past has put the British national interest first in looking at this issue."
Speaking in the Commons, the prime minister added that we "cannot afford to relax our guard" and "need to be prepared to deter threats to our lives and our livelihoods."
A schizophrenic man who murdered a "wholly innocent" engineer while on a drugs binge has been jailed for life.
Jobless Robert Kay, 49, walked past the open garage of Ian Dollery's seaside home in St Annes, Lancashire, and stabbed him in front of his screaming wife, Andrea, and their 22-year-old daughter, Grace.
The attack took place on the evening of June 18 last year just hours before the Dollerys were due to go holiday and after the defendant had injected himself with amphetamines and drunk eight cans of Tennent's Super lager.
Before the murder, Kay had told friends he was "the son of Satan" and had been given "a list of things to do".
The court was told Grace Dollery used a broomstick to force Kay, armed with a large kitchen knife, out of the garage of the detached property in York Road.
Father-of-three Mr Dollery, who worked at BAE Systems all his life, suffered more than 30 stab wounds, some made with considerable force, and later died in hospital.
Kay - who had never met his victim - had admitted manslaughter on the grounds of diminished responsibility but a jury at Preston Crown Court convicted him of murder.
The defendant was suffering from a long-standing illness at the time of the killing but had failed to co-operate with mental health services over the years, the court heard.
"My life, and that of my family and friends, has been shattered into tiny pieces never to be restored
"I am only here today because of my daughter's courage and quick thinking."
“This is a tragic case in which Ian Dollery was murdered in a random and senseless attack.
“He was cruelly taken away from his family by Robert Kay, a man who he did not know and had never met.
“Kay has now been brought to justice for his actions but I am aware that it will not bring Mr Dollery back and nothing will ever compensate his family for their loss.
"My thoughts, and those of the officers who worked on this case, remain with them at this time.”
There's clear division over Britain's nuclear deterrent, which carries missiles as powerful as eight Hiroshima nuclear bombs.Read the full story ›
The future of ship-workers in Barrow will be decided later as MPs vote on whether to replace the Trident nuclear submarines built there.Read the full story ›
MPs are set to vote on Monday evening whether or not to renew Britain's £40 billion Trident nuclear deterrent.Read the full story ›
Alison Mackenzie interviews the Labour leadership contender and Wallasey MP Angela Eagle, and debates Brexit and the Manchester Mayoral contest with Conservative MEP Sajjad Karim and Labour MP for Blackley and Broughton .