Corbyn has long campaigned against nuclear weapons, having been a member of the Campaign for Nuclear Disarmament (CND) and the national chair of the Stop the War Coalition from June 2011 until September 2015.
He is at odds with the rest of his party over his stance on Trident — the UK's nuclear deterrent consisting of nuclear weapons carried aboard Vanguard class submarines. The current fleet is coming up for replacement and there is a huge debate over their replacement.
Both UK Prime Minister David Cameron's Conservative and the Labour Party support the replacement of the current Trident program. It is current Labour Party policy, as voted on at the annual conference.
Corbyn — who was elected Labour leader in a surprise result after party supporters were able to gain party membership for just US$4.29, which boosted a surge in left-wing support for him — wants to change party policy so that Trident is not replaced.
Lets keep Trident but without any nuclear warheads says Corbyn..Mad as a bunch of frogs. Labour all my life but he wont get my vote.— Ray Steggles (@Leicester_Fan) January 17, 2016
He moved anti-nuclear lawmaker Emily Thornberry to the position of shadow defense secretary and appointed anti-nuclear ex-London Mayor Ken Livingstone to conduct a review of Labour defense policy.
However, his anti-Trident stance is at odds with the Labour-supporting unions, who say any move to not replace Trident will lead to the loss of thousands of jobs, with the Labour Party claiming 19,000 jobs depending on Trident in Scotland alone.
Fears that the non-replacement of Trident would lead to thousands of job losses — and a dive in union membership and party support — prompted Corbyn to declare that the UK could keep its Trident nuclear fleet without carrying any warheads.
So. We have aircraft carriers with no aircraft. Now Corbyn wants Trident submarines with no missiles. Ironical, or what?— Roger Helmer (@RogerHelmerMEP) January 18, 2016
Fearful of the loss of jobs on building replacement submarines, Corbyn said they would be built, but:
"They don't have to have nuclear warheads on them."
His move was treated with derision in Monday's London newspapers, with The Sun running the headline: "Off his war head" and the left-wing Labour-supporting Daily Mirror running a cartoon showing a submarine with the instructions: "Load tube 1 with a strongly worded letter and tube 2 with a custard pie… a big one, mind/"
The Metro provided a picture of a submarine named "HMS Impotence." The Times had a similar submarine, flying a flag with "Bang" written on it.
Twitter was equally derisive, with many calling Corbyn "delusional" and "insane."