I think the unilateralist arguments traditionally put by the left aren't terribly encouraging or convincing.The only coherent position I've encountered came from erstwhile comrades of mine, who, from a class struggle perspective, argued for the disarming of the state by the revolutionary party as it prosecutes the fight for working class power. Yet once the party is in power it should then be willing to utilise existing stocks or develop new weapons to defend the revolution from counterrevolutionary interventions. No weapons are too good (or destructive) for the workers' militias, it seems. Also, take the SNP's "unilateralism", which got a good airing in the run up to the referendum. This is less coherent and far more cowardly. An independent SNP Scotland could be nuclear-free, and no large target for first strikes would be sat there on the Clyde. Yet Scotland is protected from existential external threats, because it'll happily sit under America's nuclear umbrella. The SNP then are giving up nukes, but not really giving up the perceived security of nukes by handing it over to the US instead. Nor are the moralistic arguments around unilateral disarmament particularly compelling. Regrettably, dumping Britain's nukes aren't going to inspire other countries to get shot of theirs. Slightly different circumstances I know, but the removal of nuclear weapons from Ukraine, Belarus, and Kazakhstan did little to boost disarmament movements in the West or elsewhere. The abandonment of nuclear weapons programmes by the ancien regime in Libya and currently in Iran isn't going to see Israel scrap their weapons, or prevent Saudi Arabia from reported attempts at buying a bomb or two.
Unfortunately, for those who wouldn't like to see Trident renewed and the weapons scrapped, the logic of their opponents is simple, if not coherent. The world is a scary place and an always-at-sea deterrent is the ultimate insurance policy. Suicide bombers aren't going to be warned off by submarines, but a future nuclear-armed threat might be. Whether it stands up to scrutiny of the international balance of forces or not, it offers illusory promises of security and latterly of prestige. And when anxiety gifted the Tories the general election, and could easily do so again, promising to clear out Britain's nuclear arsenal only heightens those fears. Unilateralism is to Labour's electoral prospects what cyanide pills are to one's respiration.
In the year the Tories are staring into the abyss over Europe, Labour runs the risk of not taking a historic opportunity to give them the shove into it. The leadership are intent on reopening a potentially ruinous debate marginal to people's concerns. It doesn't have to be like this. From my reading of the party, there is very little appetite even among the left for revisiting this issue. Yes, opposition to Trident renewal is a touchstone for socialist opinion in the party, but so is stopping council housing sell offs, protecting the NHS from private profiteering, and so on. It is an issue among a constellation of issues, and s not really salient except for a determined few. Most lefts would also recognise that scrapping Trident, abandoning nukes, and giving the savings to hospitals and schools transmutes gold into electoral lead. Good for lining one's bunker, not so good for winning town halls and holding on in Wales come May. There is, however, a compromise solution that might be temporarily acceptable (at least for the course of this Parliament) to both sides of the nuclear fence in the party.
First is the suggestion of a free vote by the PLP on Trident replacement. It will be uncomfortable, just like last time, but preferable to an even more damaging split. Jeremy himself is considering it, and he would be wise to go for that option. Second, while Labour's present policy is for renewing Trident, it is also for the stepping up of multilateral negotiations for the global reduction of nuclear weapons, with a view to a nuclear weapons-free world. Instead of focusing attention on unilateralism and the problems with that position, it's not intercontinental ballistic missile science to turn the debate into one stressing the failings of the Tories to push non-proliferation and stockpile reduction. Britain is obligated by treaty to do this, and nothing has been done. It's an open goal that could change the conversation away from Labour's woes onto, shock horror, opposing the Tory mendacity and incompetence.
This isn't an original observation, but from the point of view of the party, of the labour movement, of our electoral chances, and of taking the fight to the Tories, it's the best hope for something resembling unity over this issue.