There is a rising tide of opposition to a Trident replacement, with military experts and senior ex-cabinet members now being joined by key figures in the Labour party in arguing against renewing our nuclear weapons programme.

The case against Trident is clear. It’s a hugely expensive and outdated weapon that does nothing to keep us safe against the threats we face today. Indeed the government’s own analysis has relegated “weapons proliferation” to being a “tier 2” threat – below far more pressing concerns such as terrorism, public health and major natural hazards.

Furthermore, our weapons system is neither independent nor a deterrent. It relies on technology and maintenance from the US, and could not conceivably be used without US consent. To attribute the absence of nuclear war to nuclear deterrence imbues nuclear deterrence with a false sense of efficacy.

In fact nuclear weapons make us less safe, not least because their very existence increases the likelihood they’ll be used, and contributes to the amount of nuclear material circulating around the world. With the added risk of a cyber-attack on a nuclear weapons system, the argument that these weapons improve our security just doesn’t stack up.

Though the movement against nuclear weapons is growing, we do have some basic parliamentary arithmetic to contend with when the vote finally comes to the House of Commons. It’s clear that, as well as winning over a chunk of Tory backbenchers, we need Labour to stand strong on this issue.

It’s with that in mind that I was sorry to hear that my fellow anti-Trident campaigner, the Labour leader Jeremy Corbyn, is considering the renewal of Britain’s Trident-capable submarine fleet – while saying he wouldn’t purchase new warheads.

The pressures on Corbyn are intense. On the one hand he has the ever-present bile pouring out of some on the right of his party, eager to attack him on every issue. At the same time he’s under pressure from trade unions which are understandably nervous about job losses in defence.

Anyone serious about ridding the UK of nuclear weapons should be honest about the need for investment in genuine job diversification. Using a highly skilled workforce to construct submersible white elephants just doesn’t make sense at a time when we could be investing in jobs for the future, like green technology and low carbon infrastructure.

Even without the warheads, the sums involved in building the submarines would be colossal. The Ministry of Defence’s own figures show that the bill for the submarines themselves make up 70% of the total procurement costs.

But beyond the need to diversify defence jobs, and the obscene costs involved in building these submarines, there is a crucial question that must be answered by anyone engaging in this debate: should Britain join the vast majority of nations in being nuclear-free, or not?

It seems clear to me that if we keep the submarines ready to be rearmed at some undisclosed point in the future, we fundamentally undermine any decision not to purchase new warheads. If we are truly committed to reducing the worldwide nuclear threat and fulfilling our obligations under the non-proliferation treaty, real disarmament is our duty. Keeping our nuclear weapons capability sends a signal to the rest of the world that security is dependent on being able to use weapons of mass destruction, and thus drives proliferation.

Genuine disarmament, alongside work with other nations to solve global threats such as fossil fuel-induced climate disruption and transnational trafficking in weapons, people and drugs, along with the poverty and desperation that fuel conflicts, hunger and violence, is the best way to reduce nuclear dangers and improve global security. Only disarmament will strengthen the non-proliferation regime, deter nuclear proliferation, de-escalate international tensions and create the conditions for the objective which president Barack Obama enshrined in 2009, “the peace and security of a world free of nuclear weapons”.

As Corbyn is now finding out, it takes real bravery to stand strong in the face of the kind of pervasive warped logic that has been at the heart of every government’s defence policy since 1945. Thankfully courage is not something that the leader of the Labour party lacks and I hope he will not give into pressure from those playing political games with our security.

Indeed as a vote on Trident approaches, MPs from all parties should note that history will not judge kindly those who deny the evidence in front of them and base their decision on the toxic cocktail of bravado and a fear of challenging the status quo.