The United States and Britain have started carrying out strikes against targets linked to Houthis in Yemen, four US officials said, the first time strikes have been launched against the Iran-backed group since it started targeting international shipping in the Red Sea late last year.
Strikes have already been carried out by aircraft, ships, and submarine, a US official said, with witnesses in the capital Sanaa reporting the sound of explosions.
Raids were conducted on several Yemeni cities, an official from the Houthi movement said.
"American-Zionist-British aggression against Yemen launches several raids on the capital, Sanaa, Hodeidah governorate, Saada, and Dhamar," Houthi official Abdul Qader al-Mortada said on X.
Mr Sunak briefed his cabinet of ministers on the imminent military intervention earlier on Thursday, the Times had reported.
British media also reported that other political figures, including the leader of Britain's opposition Labour Party, Keir Starmer, as well as the speaker of the House of Commons, had been briefed by the government.
Three residents of Yemen's Hodeidah told Reuters the city has been on alert since this Thursday evening, with the heavy deployment of Houthi forces and movement of military trucks.
Houthi military sites and camps in Hodeidah were also being evacuated, they said.
Yemen's Iranian-backed Houthi militants have stepped up attacks on commercial vessels in the Red Sea in protest against Israel's war in Gaza.
Various shipping lines have suspended operations, instead taking the longer journey around Africa.
The US military said the Houthis today staged their 27th attack on shipping since 19 November, firing an anti-ship ballistic missile into international shipping lanes in the Gulf of Aden.
Earlier this week, US and British naval forces shot down drones and missiles fired by the Houthis toward the southern Red Sea.
The Houthis, who seized much of Yemen in a civil war, have vowed to attack ships linked to Israel or bound for Israeli ports.
However, many of the targeted ships have had no links to Israel.
The UN Security Council adopted a resolution that demanded the Houthis "immediately cease" their attacks.
Washington says more than 20 nations have joined the US-led Operation Prosperity Guardian to protect the vital sea lane which usually carries about 12% of maritime trade.
The Houthi leader said that "there is no problem for the Europeans, China and the whole world to pass through the Red Sea".
"The only and exclusive target are ships linked to Israel."
But he added that any government that joins the military action against the rebels' naval forces would face reprisals.
"Whoever wants to get involved, attack our dear people and target the naval forces is actually risking their fleet and commercial ships," Houthi warned.
"We hope that the rest of the Arab and Islamic countries will never get involved with the Americans, the Israelis and the British."
It comes as Iran's navy has seized an oil tanker in the Gulf of Oman following "a court order" authorising the move, Iranian state media reported.
"The Navy of the Islamic Republic of Iran seized an American oil tanker in the waters of the Gulf of Oman in accordance with a court order," the official IRNA news agency said.
The tanker is carrying Iraqi crude oil and was destined for Turkey.
The action appears to be a retaliation for the seizure last year of the same vessel by the United States, Iranian media reported.
The Marshall Islands-flagged tanker St Nikolas was confiscated for carrying sanctioned Iranian oil in 2023, prompting Iran to warn the US that the action would "not go unanswered".
Today, the same vessel was boarded by armed intruders as it sailed close to the Omani city of Sohar, according to the British maritime security firm, Ambrey.
Its tracking system was turned off as the vessel was redirected towards the Iranian port of Bandar-e-Jask.
