Sir Keir Starmer has warned of a “risk of escalation” to the Middle East and beyond the region, as he calls for a return to the negotiating table after the US bombed Iranian nuclear sites overnight.
The prime minister said he wanted to “reassure the British public that we’re doing everything we can to stabilise the situation” and find a diplomatic solution after the US bombed three sites.
He added the government had “taken all necessary measures” to protect UK interests in the region but his focus was on de-escalation.
Sir Keir said there was no UK involvement in the US action but he was told about it in advance.
He will later chair an emergency Cobra response meeting.
The US said it had carried out strikes on three nuclear facilities in Iran: Natanz, Isfahan and Fordo on Saturday night.
US Defence Secretary Pete Hegseth said the strikes “devastated the Iranian nuclear programme”.
Iran’s foreign minister Seyed Abbas Araghchi called the US strikes “outrageous” and said they would have “everlasting consequences”.
Speaking at his Chequers country retreat, Sir Keir said escalation was a risk to the Middle East and “beyond the region”.
He added “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”.
He said the UK had been “clear Iran cannot have a nuclear weapon”, adding stability in the region was the priority.
Business Secretary Jonathan Reynolds told the BBC’s Sunday with Laura Kuenssberg programme that Iran “is a threat to this country, not in an abstract way, not in a speculative way”.
He stressed there was “simply no way a responsible British government would ever allow [Iran] to possess nuclear weapons”.
Last October, the head of MI5 said the intelligence service had responded to 20 plots backed by Iran in the UK since 2022, posing “potentially lethal threats to British citizens and UK residents”.
Ken McCallum said at the time that since the 2022 killing of Mahsa Amini – the 22-year-old who died in Iranian police custody after being arrested for allegedly violating rules requiring women to wear the headscarf – “we’ve seen plot after plot here in the UK, at an unprecedented pace and scale”.
Reynolds stopped short of welcoming the US strikes, saying he “wanted a different way to obtain this but I cannot pretend to you that prevention of Iran having a nuclear weapon is anything other than in the interests of the UK”.
Although the UK had “wanted” a peaceful de-escalation of tensions, Reynolds added: “Iran didn’t listen to the diplomatic calls for a peaceful solution. That was a mistake.”
The prime minister said the UK had been “moving assets to the region to make sure we’re in a position to protect our own interests, our personnel and our assets, and, of course, those of our allies.”
A UK defence source said British military personnel in the Middle East were now on their highest level of alert.
Only a week ago, Sir Keir met US President Donald Trump at the G7 summit in Canada, where he pushed for de-escalation, and had previously said there was “nothing” from the president to suggest he was about to get involved in the conflict.
Iran has claimed its nuclear ambitions are peaceful and recent uranium enrichment to 60% was done as part of a research and development programme.
However, the International Atomic Energy Agency’s (IAEA) latest report warned that Iran had amassed enough enriched uranium to potentially make nine nuclear bombs, which was “a source of legitimate concern”.
Asked why Iran needed uranium enriched to near weapons-grade, Iran’s ambassador to the UK, Seyed Ali Mousavi, told the BBC: “There’s no intention from our side to go into a military attack”.
He added Iran is considering the “quantity and quality” of its reaction to the US action.
Israeli President Isaac Herzog told Kuenssberg that Iran’s nuclear programme had been hit “substantially” but added that he did not yet know the exact details of what happened as he did not know in advance and was “woken up when it happened”.
Israel has been targeting military sites in Iran in recent days, with Iran returning fire.
Overnight, B-2 stealth bombers moved from a US airbase in Missouri to the Pacific island of Guam ahead of the strikes on Iran.
The UK-US airbase on Diego Garcia, one of the Chagos Islands, was not used.
In a televised address following the strikes, Trump said the US’s overnight operation was a “spectacular military success”, adding that if Iran did not make peace quickly it would face “far greater” attacks.
No increase in off-site radiation has been reported, according to the UN’s International Atomic Energy Agency (IAEA) latest update.
UN Secretary General António Guterres said the overnight strikes were a “dangerous escalation”.
Reacting to the US action, Conservative leader Kemi Badenoch, said: “By targeting Iran’s nuclear sites, the US has taken decisive action against a regime that fuels global terror and directly threatens the UK.”
Liberal Democrat leader Ed Davey said it was now “essential” for the UK to “de-escalate the conflict and achieve that diplomatic solution”.
Starmer has previously urged further negotiations in a bid to de-escalate the conflict.
Foreign Secretary David Lammy travelled to Washington last week to meet Secretary of State Marco Rubio and US special envoy Steve Witkoff.
The foreign secretary said after the meeting: “We discussed how a deal could avoid a deepening conflict. A window now exists within the next two weeks to achieve a diplomatic solution.”
He formed part of a European contingent which met with Iranian officials on Friday.
The Foreign, Commonwealth and Development Office (FCDO) has advised against all travel to Israel and the Occupied Palestinian Territories and Iran.
On Sunday, British Airways announced it was pausing flights to Dubai in the United Arab Emirates and Doha in Qatar in light of the situation.
In a statement, a spokesperson said the airway’s flight schedule had been adjusted “to ensure the safety of our customers and crew”, adding customers had been contacted and advised of their travel options.
It is understood all flights to the airports scheduled to leave London Heathrow on Saturday, and their subsequent return flights, were cancelled.
Those due to travel up until Tuesday are able to rebook free of charge onto a later flight up to and including 6 July.
