The Houthis' attacks risk worsening the "dire humanitarian situation" in Yemen itself, continues Sunak.
He points out that food aid for hundreds of thousands of Yemenis arrives via "the very sea routes the Houthis have in their sights".
Sunak says that the UK is prepared to "back our words with actions."
He adds that these military actions do not detract from other international commitments, but instead strengthen the UK's determination to uphold "fundamental UN principles".
If our enemies think they can distract us from our obligations in Ukraine, he says, "they could not be more wrong".
Post update
The prime minister says he has attempted to resolve the issue with diplomacy, saying the Houthis were given "clear and unambiguous warning" and that the UN Security Council already passed a resolution condemning the Houthis' attacks.
He echoes defence secretary Grant Shapps' argument that attacks on Houthi targets are "completely unrelated" to the Israel-Gaza conflict.
"We shouldn't fall for their malign narrative that this is about Israel and Gaza... [UK strikes are] a direct response to the Houthis' attacks on international shipping," he says.
He stresses that inaction risks sending "a dangerous message that British vessels and British interests are fair game".
Operation was 'limited, not escalatory', Sunak says
Video content
Video caption: PM: This action was taken in self-defencePM: This action was taken in self-defence
Sunak says to maximise security and effectiveness of the operation it was not possible to "bring the issue to the House in advance".
He adds that he went to the House at the earliest possible opportunity.
"I don't take decisions on the use of force lightly. It was limited, not escalatory. It was a necessary and a proportionate response to a direct threat to the UK vessels, therefore to the UK itself."
Sunak says that the Royal Navy is in the Red Sea as part of Operation Prosperity Guardian.
"The Houthis' attacks on international shipping have put innocent lives at risk. They have held one crew hostage for almost two months. And they are causing growing economic disruption," he adds.
Sunak: Houthi launch sites for drones and ballistic missiles destroyed
House of CommonsCopyright: House of Commons
Sunak says that 13 targets - which were Houthi launch sites for drones and ballistic missiles - were destroyed.
He adds that there is no evidence thus far of civilian casualties, "which we took great care to avoid," he says.
'They fired on our ships and our sailors'
Rishi Sunak begins by saying that he wants to update the Commons on the action the UK took on Thursday night to target Houthi military targets in Yemen.
He says that since 16 November, the Houthis have launched 25 "illegal" and "unacceptable" attacks in the Red Sea.
He says the attack on 9 January was the "biggest attack on the Royal Navy for decades.
"They fired on our ships and our sailors. It was the biggest attack on the Royal Navy for decades and so we acted," he says.
The strikes were "limited" and "carefully targeted" to degrade Houthi capacity to make further attacks, he adds.
Sunak begins delivering a statement
Prime Minister Rishi Sunak is on his feet and has begun addressing MPs in the House of Commons.
Stay with us as we bring you what he says.
US-owned cargo ship was hit by Houthi missile - Centcom
The US-owned M/V Gibraltar Eagle has been identified as the ship hit by a ballistic missile which was fired by the Houthis, according to United States military command for the Middle East (Centcom).
Earlier, maritime security agency Ambrey had confirmed that the missile was one of three fired by the Houthis. The other two did not reach the sea.
Sunak to address Parliament shortly
We are expecting a statement in the House of Commons from UK Prime Minister Rishi Sunak at about 15:30 GMT.
He is expected to to speak about the UK's role in the attacks against the Houthis in Yemen.
You can follow the statement through our updates or watch it by pressing Play at the top of the page.
Analysis
Three options on the table for the Houthis
Frank Gardner
BBC security correspondent
The Houthis, who control most of the populated parts of Yemen, now have three options.
They can back down, having made their point, raised their regional profile and increased their popularity at home.
Their actions to date show no sign of them doing this.
They can continue to harass military and commercial shipping off their coasts, which they appear to be now doing.
Or - and this is the option the West should worry about - they could marshal their remaining missiles and drones and wait for the opportunity to launch a mass attack on a US or British warship, in the hopes of overwhelming its air defences. This is something the Houthi spokesman has already hinted at and it remains a real risk.
US intelligence assesses that the recent airstrikes on the Houthis’ military facilities have destroyed or degraded around a quarter of their arsenal.
Further airstrikes will degrade that further so the Houthis will need to make some careful calculations as to how far they take this beyond their fiery rhetoric about retaliation.
BreakingVessel hit by missile was US-owned cargo ship - UK security firm
British maritime security firm Ambrey says the vessel struck by a missile off the south coast of Yemen was a US-owned cargo ship.
According to Ambrey, the attack "targeted US interests in response to US military strikes on Houthi military positions in Yemen".
Ambrey reports that a fire broke out on board the Marshall Islands-flagged, US-owned bulk carrier, but it remains seaworthy and there were no injuries.
It says the vessel was "assessed to not be Israel-affiliated".
The United Kingdom Maritime Trade Operations security agency said earlier that the master of a vessel reported that it had been "hit from above by a missile" near Yemen's southern port city of Aden.
Houthi navy insists ships not linked to Israel are 'safe'
Houthi-run Al Masirah TV is citing a source in the rebel group’s
naval forces as reiterating that they will not target commercial shipping not
linked to Israel.
“Navigation is safe” in the Red Sea, the Arabian Sea and
the Bab al-Mandab Strait “except for Israeli ships or those heading to occupied
Palestinian ports”, the source says.
“We will continue the prevention of Israeli
ships or those bound for occupied Palestinian ports until the end of the aggression
and siege on Gaza,” they add.
Since November, the Houthis have attacked merchant
vessels in the Red Sea more than 20 times with missiles, drones, fast boats and
helicopters. They have claimed - often falsely - that those ships were
linked to Israel.
Vessel reported being hit by missile - UKMTO
More now on the "incident" in Yemeni waters, as reported by the UK Maritime Trade Operations (UKMTO).
The UKMTO says the master of the vessel says the boat was "hit from above by a missile" near Yemen's southern port city of Aden.
It's unclear who is behind the strike but we'll update you with information as we have it.
BreakingUK maritime trade reports 'incident' off Yemen coast
The UK Maritime Trade Operations (UKMTO) is reporting an "incident" 95 nautical miles southeast of Yemen's port city of Aden.
It says authorities are investigating and has advised vessels in transit to exercise "extreme caution".
The UKMTO hasn't said what the incident is in relation to but we'll bring you more information on the situation as we get it.
Watch: Yemen strikes were a 'last resort', says Sunak
Prime Minister Rishi Sunak says the strikes on Houthi targets in Yemen were a "last resort" following "exhaustive diplomatic activity".
"We of course will not hesitate to protect our security where required," says Sunak during a visit to Essex today.
Video content
Video caption: Sunak says he will not hesitate to act against Houthi targets againSunak says he will not hesitate to act against Houthi targets again
Analysis
So, will there be more UK-US strikes on Yemen?
Harry Farley
Political correspondent
One of the big questions this morning is, will the government
launch more strikes against the Houthis in Yemen?
UK Prime Minister Rishi Sunak and Defence Secretary Grant Shapps have both been asked that this morning - and neither of them ruled it out.
The aim was to "de-escalate tensions in the
region," Rishi Sunak said on a visit to Essex. "But we, of course,
will not hesitate to protect our security where required."
Another question is why the
government did not consult MPs before launching this action.
The Liberal Democrats have called for a new law that would
mean MPs must have a vote before military action is launched. But the political pressure on Sunak over this is
limited.
Labour leader Sir Keir Starmer has said he understands that "when urgent operational issues arise", it’s not possible to have a vote in the
Commons beforehand. He also said there’s a "distinction" between "one off operations
the like of which we’ve seen in the last few days" and "sustained" military
campaigns.
Which, again, raises the question - will these strikes
happen again?
We won’t hesitate to act again - UK prime minister on Houthi strikes
BBCCopyright: BBC
In the last few minutes, Rishi Sunak has been speaking to reporters on a visit to Essex, where the prime minister says the UK "will not hesitate" to take further action against the Houthis to protect British security in the Red Sea.
"We faced an escalating series of attacks from the Houthis on commercial shipping, including an attack on a Royal Navy warship," he says, adding this was "unacceptable".
Pushed on the matter, he says the military action taken by the UK last week was a "last resort" designed to "de-escalate tensions in the region" and "restore stability".
Sunak's due to address MPs later today about the US-UK strikes in Yemen, which were launched over the weekend.
As we've been hearing, the Houthis' chief negotiator Mohammad Abdulsalam has just warned that the group intends to continue striking ships "heading to the ports of the occupied Palestine".
BreakingHouthi chief negotiator warns attacks will continue
Reuters news agency has spoken to the Houthi chief negotiator, Mohammed Abdulsalam, who says the group's position on the war in Gaza has not changed following US-UK strikes on Yemen.
He's also quoted as saying the Houthis will continue their attacks on ships which are headed to Israel.
"Attacks to prevent Israeli ships or those heading to the ports of the occupied Palestine will continue," Abdulsalam says, in what is the group's first response to strikes over the weekend.
He says the group's demands are still for an end of Israeli attacks on Gaza, and allowing humanitarian aid to reach the north and south of the Strip.
Six things to know this lunchtime
ReutersCopyright: Reuters
If you're just joining us, or need a bit of a recap, here's how things are looking:
UK Defence Secretary Grant Shapps said during his first major speech in the role that Houthis were given "every possible warning" to cease and desist before US-UK strikes were launched on targets inside Yemen
He wouldn't say if more action was planned but officials are monitoring the situation "very carefully" to see what the rebel group does next, he told reporters
A reminder: Iran-backed Houthi rebels, based in Yemen, began attacking commercial shipping in the Red Sea late last year - they claim they're targeting vessels heading to, or owned by, Israel, as an act of solidarity with the people of Gaza
As a result of the attacks, many of the world's biggest shipping companies have stopped vessels using the Red Sea route, with an economist warning this could have a knock-on effect with inflation (check out our last post)
Late last night, the US military said it had shot down a missile fired towards one of its warships from a Houthi-run area - the group hasn't commented on the action
And this afternoon we'll hear from UK Prime Minister Rishi Sunak, who's due to address British MPs about the government's decision to join US strikes on Houthi targets - a move that was authorised without consulting Parliament
Inflation risk from shipping disruption, economist warns
Dearbail Jordan
Business reporter
A bit more now on some of the effects this disruption in the Red Sea - specifically the Bab al-Mandab Strait, a vital trade route - is having around the world.
Inflation is at risk of rising again, according to leading economist Mohamed El-Erian, who says disruption to shipments is not as severe as during Covid - but it will still push up prices and hit economic growth.
"Relative to what would have happened otherwise, we will see higher inflation, higher mortgage rates and lower growth," Dr El-Erian, president of Queens' College, Cambridge and chief economic adviser at financial services giant Allianz, told the BBC's Today programme earlier.
Around 12-15% of global trade travels through the Red Sea via the Bab al-Mandab Strait - a 20-mile wide channel that splits Eritrea and Djibouti on the African side and Yemen on the Arabian Peninsula - and the Suez Canal.
Major shipping firms are now re-routing their vessels around Africa's Cape of Good Hope, which can add 12 days for cargo travelling between Singapore and northern Europe. You can see a map illustrating this change in our last post.
Grant Shapps has just been outlining why his government thought it was crucial to join US strikes on Houthi targets in Yemen.
The UK defence secretary said it was important to secure international free trade by protecting ships sailing through the Red Sea.
Our map above shows how the Houthis' attacks on those ships since mid-November have affected shipping routes - with vessels having to avoid the danger zone by sailing a longer route around southern Africa.
So far, Tesla and Volvo have suspended some of their car production, UK grocery giant Tesco has warned some prices may go up and Ikea has said supplies could be affected. QatarEnergy has also said it's pausing shipping through the Red Sea.
Live Reporting
Edited by Emily McGarvey and Nadia Ragozhina
All times stated are UK
UK prepared to 'back our words with actions'
The Houthis' attacks risk worsening the "dire humanitarian situation" in Yemen itself, continues Sunak.
He points out that food aid for hundreds of thousands of Yemenis arrives via "the very sea routes the Houthis have in their sights".
Sunak says that the UK is prepared to "back our words with actions."
He adds that these military actions do not detract from other international commitments, but instead strengthen the UK's determination to uphold "fundamental UN principles".
If our enemies think they can distract us from our obligations in Ukraine, he says, "they could not be more wrong".
Post update
The prime minister says he has attempted to resolve the issue with diplomacy, saying the Houthis were given "clear and unambiguous warning" and that the UN Security Council already passed a resolution condemning the Houthis' attacks.
He echoes defence secretary Grant Shapps' argument that attacks on Houthi targets are "completely unrelated" to the Israel-Gaza conflict.
"We shouldn't fall for their malign narrative that this is about Israel and Gaza... [UK strikes are] a direct response to the Houthis' attacks on international shipping," he says.
He stresses that inaction risks sending "a dangerous message that British vessels and British interests are fair game".
Operation was 'limited, not escalatory', Sunak says
Video content
Sunak says to maximise security and effectiveness of the operation it was not possible to "bring the issue to the House in advance".
He adds that he went to the House at the earliest possible opportunity.
"I don't take decisions on the use of force lightly. It was limited, not escalatory. It was a necessary and a proportionate response to a direct threat to the UK vessels, therefore to the UK itself."
Sunak says that the Royal Navy is in the Red Sea as part of Operation Prosperity Guardian.
"The Houthis' attacks on international shipping have put innocent lives at risk. They have held one crew hostage for almost two months. And they are causing growing economic disruption," he adds.
Sunak: Houthi launch sites for drones and ballistic missiles destroyed
Sunak says that 13 targets - which were Houthi launch sites for drones and ballistic missiles - were destroyed.
He adds that there is no evidence thus far of civilian casualties, "which we took great care to avoid," he says.
'They fired on our ships and our sailors'
Rishi Sunak begins by saying that he wants to update the Commons on the action the UK took on Thursday night to target Houthi military targets in Yemen.
He says that since 16 November, the Houthis have launched 25 "illegal" and "unacceptable" attacks in the Red Sea.
He says the attack on 9 January was the "biggest attack on the Royal Navy for decades.
"They fired on our ships and our sailors. It was the biggest attack on the Royal Navy for decades and so we acted," he says.
The strikes were "limited" and "carefully targeted" to degrade Houthi capacity to make further attacks, he adds.
Sunak begins delivering a statement
Prime Minister Rishi Sunak is on his feet and has begun addressing MPs in the House of Commons.
Stay with us as we bring you what he says.
US-owned cargo ship was hit by Houthi missile - Centcom
The US-owned M/V Gibraltar Eagle has been identified as the ship hit by a ballistic missile which was fired by the Houthis, according to United States military command for the Middle East (Centcom).
In a post on X, formerly known as Twitter, Centcom says that the vessel "has reported no injuries or significant damage and is continuing its journey".
Earlier, maritime security agency Ambrey had confirmed that the missile was one of three fired by the Houthis. The other two did not reach the sea.
Sunak to address Parliament shortly
We are expecting a statement in the House of Commons from UK Prime Minister Rishi Sunak at about 15:30 GMT.
He is expected to to speak about the UK's role in the attacks against the Houthis in Yemen.
You can follow the statement through our updates or watch it by pressing Play at the top of the page.
Three options on the table for the Houthis
Frank Gardner
BBC security correspondent
The Houthis, who control most of the populated parts of Yemen, now have three options.
They can back down, having made their point, raised their regional profile and increased their popularity at home.
Their actions to date show no sign of them doing this.
They can continue to harass military and commercial shipping off their coasts, which they appear to be now doing.
Or - and this is the option the West should worry about - they could marshal their remaining missiles and drones and wait for the opportunity to launch a mass attack on a US or British warship, in the hopes of overwhelming its air defences. This is something the Houthi spokesman has already hinted at and it remains a real risk.
US intelligence assesses that the recent airstrikes on the Houthis’ military facilities have destroyed or degraded around a quarter of their arsenal.
Further airstrikes will degrade that further so the Houthis will need to make some careful calculations as to how far they take this beyond their fiery rhetoric about retaliation.
BreakingVessel hit by missile was US-owned cargo ship - UK security firm
British maritime security firm Ambrey says the vessel struck by a missile off the south coast of Yemen was a US-owned cargo ship.
According to Ambrey, the attack "targeted US interests in response to US military strikes on Houthi military positions in Yemen".
Ambrey reports that a fire broke out on board the Marshall Islands-flagged, US-owned bulk carrier, but it remains seaworthy and there were no injuries.
It says the vessel was "assessed to not be Israel-affiliated".
The United Kingdom Maritime Trade Operations security agency said earlier that the master of a vessel reported that it had been "hit from above by a missile" near Yemen's southern port city of Aden.
Houthi navy insists ships not linked to Israel are 'safe'
Houthi-run Al Masirah TV is citing a source in the rebel group’s naval forces as reiterating that they will not target commercial shipping not linked to Israel.
“Navigation is safe” in the Red Sea, the Arabian Sea and the Bab al-Mandab Strait “except for Israeli ships or those heading to occupied Palestinian ports”, the source says.
“We will continue the prevention of Israeli ships or those bound for occupied Palestinian ports until the end of the aggression and siege on Gaza,” they add.
Since November, the Houthis have attacked merchant vessels in the Red Sea more than 20 times with missiles, drones, fast boats and helicopters. They have claimed - often falsely - that those ships were linked to Israel.
Vessel reported being hit by missile - UKMTO
More now on the "incident" in Yemeni waters, as reported by the UK Maritime Trade Operations (UKMTO).
The UKMTO says the master of the vessel says the boat was "hit from above by a missile" near Yemen's southern port city of Aden.
It's unclear who is behind the strike but we'll update you with information as we have it.
BreakingUK maritime trade reports 'incident' off Yemen coast
The UK Maritime Trade Operations (UKMTO) is reporting an "incident" 95 nautical miles southeast of Yemen's port city of Aden.
It says authorities are investigating and has advised vessels in transit to exercise "extreme caution".
The UKMTO hasn't said what the incident is in relation to but we'll bring you more information on the situation as we get it.
Watch: Yemen strikes were a 'last resort', says Sunak
Prime Minister Rishi Sunak says the strikes on Houthi targets in Yemen were a "last resort" following "exhaustive diplomatic activity".
"We of course will not hesitate to protect our security where required," says Sunak during a visit to Essex today.
Video content
So, will there be more UK-US strikes on Yemen?
Harry Farley
Political correspondent
One of the big questions this morning is, will the government launch more strikes against the Houthis in Yemen?
UK Prime Minister Rishi Sunak and Defence Secretary Grant Shapps have both been asked that this morning - and neither of them ruled it out.
The aim was to "de-escalate tensions in the region," Rishi Sunak said on a visit to Essex. "But we, of course, will not hesitate to protect our security where required."
Another question is why the government did not consult MPs before launching this action.
The Liberal Democrats have called for a new law that would mean MPs must have a vote before military action is launched. But the political pressure on Sunak over this is limited.
Labour leader Sir Keir Starmer has said he understands that "when urgent operational issues arise", it’s not possible to have a vote in the Commons beforehand. He also said there’s a "distinction" between "one off operations the like of which we’ve seen in the last few days" and "sustained" military campaigns.
Which, again, raises the question - will these strikes happen again?
We won’t hesitate to act again - UK prime minister on Houthi strikes
In the last few minutes, Rishi Sunak has been speaking to reporters on a visit to Essex, where the prime minister says the UK "will not hesitate" to take further action against the Houthis to protect British security in the Red Sea.
"We faced an escalating series of attacks from the Houthis on commercial shipping, including an attack on a Royal Navy warship," he says, adding this was "unacceptable".
Pushed on the matter, he says the military action taken by the UK last week was a "last resort" designed to "de-escalate tensions in the region" and "restore stability".
Sunak's due to address MPs later today about the US-UK strikes in Yemen, which were launched over the weekend.
As we've been hearing, the Houthis' chief negotiator Mohammad Abdulsalam has just warned that the group intends to continue striking ships "heading to the ports of the occupied Palestine".
BreakingHouthi chief negotiator warns attacks will continue
Reuters news agency has spoken to the Houthi chief negotiator, Mohammed Abdulsalam, who says the group's position on the war in Gaza has not changed following US-UK strikes on Yemen.
He's also quoted as saying the Houthis will continue their attacks on ships which are headed to Israel.
"Attacks to prevent Israeli ships or those heading to the ports of the occupied Palestine will continue," Abdulsalam says, in what is the group's first response to strikes over the weekend.
He says the group's demands are still for an end of Israeli attacks on Gaza, and allowing humanitarian aid to reach the north and south of the Strip.
Six things to know this lunchtime
If you're just joining us, or need a bit of a recap, here's how things are looking:
Inflation risk from shipping disruption, economist warns
Dearbail Jordan
Business reporter
A bit more now on some of the effects this disruption in the Red Sea - specifically the Bab al-Mandab Strait, a vital trade route - is having around the world.
Inflation is at risk of rising again, according to leading economist Mohamed El-Erian, who says disruption to shipments is not as severe as during Covid - but it will still push up prices and hit economic growth.
"Relative to what would have happened otherwise, we will see higher inflation, higher mortgage rates and lower growth," Dr El-Erian, president of Queens' College, Cambridge and chief economic adviser at financial services giant Allianz, told the BBC's Today programme earlier.
Around 12-15% of global trade travels through the Red Sea via the Bab al-Mandab Strait - a 20-mile wide channel that splits Eritrea and Djibouti on the African side and Yemen on the Arabian Peninsula - and the Suez Canal.
Major shipping firms are now re-routing their vessels around Africa's Cape of Good Hope, which can add 12 days for cargo travelling between Singapore and northern Europe. You can see a map illustrating this change in our last post.
Post update
Grant Shapps has just been outlining why his government thought it was crucial to join US strikes on Houthi targets in Yemen.
The UK defence secretary said it was important to secure international free trade by protecting ships sailing through the Red Sea.
Our map above shows how the Houthis' attacks on those ships since mid-November have affected shipping routes - with vessels having to avoid the danger zone by sailing a longer route around southern Africa.
So far, Tesla and Volvo have suspended some of their car production, UK grocery giant Tesco has warned some prices may go up and Ikea has said supplies could be affected. QatarEnergy has also said it's pausing shipping through the Red Sea.