The UK and the US have once again carried out joint airstrikes against Houthi targets in Yemen.
Officials say the US and UK took out Houthi missile storage sites and launchers, in the second set of co-ordinated strikes against the Iran-backed militants.
The UK joined the US in carrying out strikes against the group in Yemen earlier this month, but ships have continued to be targeted along the vital Red Sea and Gulf of Aden trade routes.
Rishi Sunak and US president Joe Biden spoke on Monday evening, with the two leaders undertaking to “continue efforts alongside international partners to deter and disrupt” attacks by Houthis.
A White House readout of the call said the two leaders “reiterated their commitment to freedom of navigation, international commerce, and defending mariners from illegal and unjustifiable attacks”.
In recent days, the US launched seven rounds of airstrikes on Houthi military sites, targeting air bases under the rebels’ control and suspected missile launch sites.
Both the British prime minister and defence secretary Grant Shapps had repeatedly declined to comment on, or rule out, the possibility of further military action if Houthi attacks continued.
But Mr Sunak had told MPs last week he was “prepared to back our words with actions”.
The UK government has insisted that the strikes would not escalate the already tense situation in the Middle East, stressing the need to protect the vital shipping route.
Details were not immediately forthcoming from the Ministry of Defence about the exact nature of the UK role in the fresh operation.
But US officials said the two countries used warship and submarine-launched Tomahawk missiles and fighter jets.
The latest set of strikes could raise questions once again about the need to consult Parliament on military action. Mr Sunak was criticised for authorising the first set of strikes when Parliament was not sitting, with some MPs stressing the need for scrutiny from the Commons.
Mr Sunak had held a full Cabinet the evening before the strikes earlier this month, with the UK government also briefing Sir Keir Starmer and shadow defence secretary John Healey.
The Houthis, a Shia rebel group that has held Sanaa since 2014 and been at war with a Saudi-led coalition backing Yemen’s exiled government since 2015, have linked their attacks to the Israel-Hamas war.
However, the ships they have targeted increasingly have tenuous links to Israel – or none at all.
