Jeremy Corbyn has called for nuclear non-proliferation to be debated by the United Nations after it was revealed Britain's nuclear system experienced a "serious malfunction".
The Labour Party leader is well-known for his opposition to nuclear weapons, but re-stated his view on Sunday (22 January) after a Trident II D5 missile veered off course when it was fired from a British submarine off the coast of Florida last June.
The missile was not armed with nuclear warheads at the time of the test, but raises serious questions about the use of such weapons in a global context.
Corbyn labelled the failed nuclear test a "catastrophic error" and argued that the world's nuclear states need to debate disarming such weaponry.
Speaking on Sky News, Corbyn said: "While it wasn't armed, goodness knows what the consequences of that could have been.
"I think we need a serious discussion about that, but also let's look to the longer future.
"I've been involved in nuclear non-proliferation conference discussions for a very long time. I think this ought to be the opportunity in which we pursue a policy of discussions with all of the nuclear-weapon states – the five permanent members of the UN – as well as those others in order to bring about nuclear disarmament, in order to bring about our participation in the non-proliferation treaty, which after all was a Labour creation in the 1960s."
After an intense debate within the Labour Party about its stance on nuclear weapons at the party conference, MPs voted overwhelmingly to renew the £40bn ($50bn) Trident nuclear programme in July.
The failed nuclear test, where the missile veered off-course, took place weeks before the vote and May was aware of the incident before she made a speech defending the weapons.
However, she made no reference of the failure when she addressed the House of Commons. She is said to have justified withholding the information due to its sensitivity.
Andrew Marr, on his Sunday morning political show, repeatedly asked May about to clarify if she knew about the failure, but she repeatedly averted the question.
Anti-nuclear campaigners have described the prime minister's actions as "shocking".
Kate Hudson, general secretary for the Campaign for Nuclear Disarmament, said: "This is a very serious failure of the Trident system and there's absolutely no doubt that this would have impacted on the debate in parliament on Trident replacement. So the government's motivation for holding back this vital information is clear.
"Instead this crucial information has been revealed by a senior naval figure rather than by government at the appropriate time to inform the parliamentary debate.
"This is shocking behaviour on the part of our government and it is profoundly to be hoped that parliamentary opposition forces will hold government to account for withholding information that is crucial to our national security."
Defence Secretary Michael Fallon is expected to be called to the House of Commons to explain the test failure, with Labour MP Kevan Jones calling for an inquiry into the incident.