The US and UK launched strikes from the air and sea against Houthi military targets in Yemen in response to the movement's attacks on ships in the Red Sea.
As witnesses in Yemen confirmed explosions throughout the country to Reuters, US President Joe Biden cautioned in a statement late on Thursday he would not hesitate to take further action if needed.
"These targeted strikes are a clear message that the US and our partners will not tolerate attacks on our personnel or allow hostile actors to imperil freedom of navigation," he said.
Biden said Australia, Bahrain, Canada and the Netherlands supported the operation.
"The response of the international community to these reckless attacks has been united and resolute."
Britain's Ministry of Defence said in a statement that "early indications are that the Houthis' ability to threaten merchant shipping has taken a blow".
US Defence Secretary Lloyd Austin, who is in hospital due to surgery complications, said in a statement that the strikes targetted Houthi capabilities including drones, ballistic and cruise missiles, costal radar and air surveillance.
Witnesses told Reuters that the raids targetted a military base adjacent to Sanaa airport, a military site near Taiz airport, a Houthi naval base in Hodeidah and military sites in Hajjah governorate.
The Houthis, who control most of Yemen, defied UN and other international calls to halt their missile and drone attacks on Red Sea shipping routes and warnings from the US of consequences if they failed to do so.
Since late December, the Houthis have attacked 27 ships, disrupting international commerce on the key route between Europe and Asia that accounts for about 15 per cent of the world's shipping traffic.
The Houthis said on Thursday any US attack on the group would not go without a response.
The overnight strikes in Yemen came just days after the Houthis' largest attack to date on January 9 in the Red Sea, which forced the US and British naval forces to shoot down 21 Houthi drones and missiles fired towards the southern Red Sea. The US military described it as a complex attack.


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