A huge US bomber capable of carrying 24 cruise missiles has landed in the UK.
The 146ft (44.5m) B-1 Lancer arrived at RAF Fairford in Gloucestershire on Friday.
It comes after Sir Keir Starmer granted the US permission to use British military bases but only for defensive strikes on Iranian missile sites.
Western officials said earlier this week that the UK was ready to accept the bombers and expected them to arrive within the next few days.
Piloted by a crew of four, the aircraft has a wingspan of 137ft (41.8m), weighs 86 tonnes and is the fastest bomber in the US Air Force, according to Boeing, hitting speeds of more than 900mph (1,448.4km/h).
US Defence Secretary Pete Hegseth said on Thursday the strikes on Iran were “about to surge dramatically”.
“It’s more fighter squadrons, it’s more capabilities, it’s more defensive capabilities. And it’s more bomber pulses more frequently,” he said.
With the Gulf States having found themselves increasingly targeted by Iran in the conflict, Sir Keir spoke to Saudi Crown Prince Mohammed bin Salman on Friday.
Sir Keir assured the kingdom’s de facto leader that the UK “stood ready to support the defence of the kingdom” if needed, a Downing Street spokeswoman confirmed.
The prime minister said “additional British fighter jets, helicopters and a destroyer were being sent to the region”, the spokeswoman said.
“The leaders also discussed stepping up intelligence cooperation to support defensive operations and protect civilians.”
Concerning energy, the Crown Prince laid out “steps the kingdom had taken to boost global oil supply and support market stability,” the spokeswoman said.
Nicknamed “the Bone”, the US bomber has advanced radar and GPS systems to help hit targets, and electronic jammers, radar warnings and a decoy system to protect it from enemies.
RAF Fairford, located on the border of Gloucestershire and Wiltshire, has been used by the US in the past to conduct long-range heavy bombing missions.
While the UK has given permission for the US to use British bases to conduct defensive strikes on the facilities, it has not taken part in the action itself.
RAF jets have been shooting down missiles and drones fired by Iran at allies in the region.
But speaking to BBC Breakfast, Conservative leader Kemi Badenoch said: “They need to do more than that, they need to stop the missile sites, you need to go to the source.”
Badenoch has stepped up her calls for the government to allow RAF to strike Iran’s missile launch sites.
“You can’t always wait for people to attack you. Sometimes you have to make sure that you get there first to stop their ability to hurt your citizens,” she said. She added that she did not want to see “troops on the ground”.
Earlier on Friday, the prime minister’s spokesman told reporters: “We’ve been very clear that our response has been to allow the US limited, specific and defensive use of our bases to protect British lives, British interests and our allies in the region.”
He added that the UK military was focused on shooting down drones in the air, while the US targets missile launch sites in Iran.
“We have consistently said that we’ll take the necessary steps to prevent future strikes which, as we’ve set out over the course of the week, is allowing the US to take out those missiles at source whilst we are defending the skies.”
