The future of a fragile Labour government may well be written some 4000 miles away in the Straits of Hormuz. As the Iran crisis deepens and consumers feel anxiety about the impact on energy and petrol prices, a party leadership that sought to position itself as sceptical of involvement in the conflict finds itself drawn further in as the stakes rise.

The Strait are the world’s most critical oil and liquified natural gas trade route and Iran intends to make them unpassable for cargo. They are already uninsurable. This is the single biggest factor now re-calibrating the international response to the war. Whether or not Donald Trump’s onslaught in Iran was a good idea, the question is what a party and public divided about the consequences does next.

Keir Starmer had wanted to reassure his already unquiet party that he was not simply going to be a passenger on a US-Israeli mission. But he finds himself in a new Catch 22: whichever way he moves, many people in his own ranks will be angry or disappointed.

Ed Miliband, the energy secretary and one of the most sceptical Cabinet voices, is Exhibit A. Yesterday, he appeared on the BBC, citing Starmer’s original decision not to join the attack on Iran as derived from the “lessons of Iraq”. Labour’s thinking on the crisis is overwhelmingly framed through the lens of Iran as potentially “another Iraq”. And that reductive approach sends the message, echoed by the Cabinet, that the more we stay away, the better.

This posture held up across a lot of the Labour party until Iran engaged in a scattergun retaliation across the Gulf. That endangered British allies and demanded a defensive response from a UK military, which, for all its weaknesses, can project force in a way that no other European power outside France can. The circle Starmer cannot easily square is this: how getting drawn more closely into the conflict – thanks to expertise in shooting down Iranian drones and sending more ships to protect the Straits (the signs are this will happen in some form) – fits with the proposition that Britain is not really that involved at all.

This is a problem for ministers. They are fretting about ending up with the reputation for being dragged into the war while claiming that their real aim is to “de-escalate”. The problem is they have zero ability actually to achieve that beyond the rhetoric of a phone-in caller.

Miliband used those words on Laura Kuenssberg’s BBC show, fully in the knowledge that it is code in Labour speak for “let’s get out of this as fast as we can.” Pushed on whether he was confident about the outcome of the conflict, we got the ultimate evasion: “Tempting as it is to talk about this in a public setting…”

But this is very much a public setting. And there are already widely differing ways of framing where the UK is heading in its commitment to be a strong player in the defence of Gulf allies, while claiming that it has not breached international law by aiding outright attacks on Tehran. There are further headwinds. Britain is one of the few main US allies, along with France, which can send more ships as part of a motley international effort demanded by Trump. And while it is unpleasant that Trump is so unnecessarily rude to Starmer about refusing the initial use of UK bases, London is now giving Washington everything it requires for assistance.

Do not take my word for that. The newly appointed US ambassador, Christian Turner, issued a crisp video at the weekend, which carefully aligned the UK with several key goals of the administration. It said: “The UK continues to act. British pilots are in the skies shooting down Iranian drones and missiles, US aircraft are using UK bases, rapidly increasing ability to strike missile facilities – and highlighting the sharing of UK-US intelligence”, concluding,” We are determined to keep the Straits of Hormuz open.”

I am with Turner on this (although the “continues” bit is a stretch). But what it is not is a plan to “de-escalate”, because it is a hefty presence and exposes the UK military to retaliation. In essence, the British ambassador to Washington, along with Defence Secretary John Healey and the Prime Minister, are now in an escalating situation.

However, Israel’s aim of degrading Iran’s nuclear threat and the US, which has variable war aims, still needs something closer to a clear “win” to satisfy Trump, the mercurial Commander in Chief.

Labour MPs are uneasy about this for good reason. Hawkish sorts, including MPs I speak to with armed forces experience, believe conflict has begun and that it is fine to wield force at scale. That is the UK military doctrine. But this is not without risk and cost. The flying hours our US ambassador refers to are also a huge drain on the UK defence budget, which is already under massive strain.

The looming political question is how long the “soft left” of Labour, already impatient with Starmer, will put up with this position of being involved in the Straits crisis, while claiming to want to get out of it as quickly as possible. Now that Trump has requested allies send ships to the Gulf (the latest loyalty test applied from Washington), that question will become more pressing because it exposes our assets as targets for Tehran.

For Greater Manchester Mayor Andy Burnham, still considering whether to make another play for another seat if a veteran MP stands down in St Helens in the near future, the present situation has been a chance to roll out the argument that this clash “parallels Iraq” and that Trump’s goal of regime change is “simplistic”. And while that is an argument Starmer himself might warm to, it is not one he can foreground when UK forces are directly engaged. That leaves this flank open to prospective challengers to show their stripes – and channel Labour angst.

Former deputy prime minister Angela Rayner has hedged her bets to date. For Labour’s deputy leader Lucy Powell, the whole saga is proof that the UK must end dependence on fossil fuels – a Greens-facing argument, but not much help if you need to decide whether to send a warship and submarine right now. The danger for the prospective challengers is that they sound out of touch with the seriousness of the conflict – and less than fit to face the choices Starmer has had to make. The risk for him is that he now has to amp up the UK’s military presence, having signalled that he did not want to do this. It would be surprising if this happens without more schisms in a fractious party, divided on how far to go along with Trump’s adventures.

Is the UK more in than out of a burgeoning conflict? It depends on who you ask in Government and on which narrow specifications. My guess is that Labour’s internal battles about what that means are only just starting.

Anne McElvoy is executive editor at Politico and host of Politics at Sam and Anne’s

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