Preventing Iran obtaining a nuclear weapon is a “good thing” for the UK, Downing Street said, as it declined to comment on whether US strikes on the country were legal.
A Number 10 spokesman said the Government’s focus remained on securing a diplomatic solution in the wake of the American attack against Iran’s nuclear programme over the weekend.
He said: “We’re clear that the prevention of Iran getting nuclear weapons is a good thing for this country.
“But our focus is on diplomacy. That is the priority and that is what every member of this Government is working towards and that’s been the focus of the calls with international partners over the weekend.”
But asked whether the strikes had breached international law, the spokesman declined to comment, citing the “long-standing position” that the Government does not disclose the content of legal advice.
Earlier, Foreign Secretary David Lammy urged Iran to take a diplomatic “off-ramp” and engage in talks, as he cautioned Tehran against blockading the Strait of Hormuz or attacking US bases in the Middle East.
Questions are being asked about whether the shipping channel or oil exports through it could be blocked amid the tensions.
Important discussion with @SecRubio this evening on the situation in the Middle East.
— David Lammy (@DavidLammy) June 22, 2025
We will continue to work with our allies to protect our people, secure regional stability and drive forward a diplomatic solution.
Speaking to BBC Breakfast on Monday morning, Mr Lammy said he had been “crystal clear” that “it would be a huge, catastrophic mistake to fire at US bases in the region at this time. We have forces in the region at this time.
“It would be a catastrophic mistake. It would be a mistake to blockade the Strait of Hormuz.”
He said he thinks his counterpart “gets that and understands that”.
The UK has been pressing for Iran to engage in negotiations and diplomacy over the issues, and Mr Lammy told the same programme: “Let’s take the diplomatic off-ramp. Let’s get serious and calm this thing down.”
Mr Lammy is expected to address MPs in the Commons about the situation on Monday.
Prime Minister Sir Keir Starmer warned on Sunday that there is a risk of the crisis escalating beyond the Middle East, telling reporters “that’s a risk to the region. It’s a risk beyond the region, and that’s why all our focus has been on de-escalating, getting people back around to negotiate what is a very real threat in relation to the nuclear programme.”
Sir Keir spoke to US President Donald Trump on Sunday, and Downing Street said the leaders agreed Tehran must not be allowed to develop a nuclear weapon and called for Iran to return to negotiations.
The conversation came after the air raid by American B-2 stealth bombers and a salvo of submarine-launched missiles hit Iran’s nuclear facilities.
“They discussed the actions taken by the United States last night to reduce the threat and agreed that Iran must never be allowed to develop a nuclear weapon,” Downing Street said.
Mr Lammy declined to say on Monday whether the US military action was legal, but added: “I don’t say it’s not legitimate”.
During an interview on BBC Radio 4’s Today programme, it was put to him that it was extraordinary he could not answer the question as critics argue Iran is also a sovereign nation which was attacked without warning.
He said: “I don’t think it is extraordinary because this was not the UK’s action, we were not involved, we were clear when this began and Israel’s attacks began that we were not involved… so I don’t say it’s not legitimate, but I can tell you as Foreign Secretary that we were not involved.”
Chancellor Rachel Reeves was asked about the legality of the strikes as she visited the West Midlands, and said: “It is up to the US to make that case. We were not involved in these actions and, of course, we would never comment on the legal advice that the Government receives.”
— Donald J. Trump (@realDonaldTrump) June 21, 2025
Mr Lammy also suggested that the action by Mr Trump “may well have set back Iran several years”.
He told the same BBC radio programme that the US president’s rhetoric was “strong” but that strikes had been “targeted” to “deal with Iran’s nuclear capability”.
The Foreign Secretary later added: “Donald Trump made a decision to act to degrade that capability. It may well have set back Iran by several years. That was a decision that he took.”
Liberal Democrat leader Sir Ed Davey has called on the Prime Minister to address the Commons about the situation in the Middle East.
He called Mr Trump’s strikes a “seismic moment” and added: “UK ministers are dodging questions on whether they support these strikes, and failing to guarantee that we won’t be dragged into another illegal American war in the Middle East.
“The Prime Minister has not even spoken once in the Commons since this crisis began. He needs to come to Parliament today, update the country on where the UK stands and what he is doing to ensure the situation does not escalate any further.”
Overnight, Mr Trump called the future of the Iranian regime into question, posting on his TruthSocial platform: “It’s not politically correct to use the term, ‘Regime Change,’ but if the current Iranian Regime is unable to MAKE IRAN GREAT AGAIN, why wouldn’t there be a Regime change???”
It appeared to be a different approach to that of his defence secretary Pete Hegseth, who had said on Sunday that “this mission was not and has not been about regime change”.
