Fighters from the Iran-backed Houthi movement have "taken control" of a key island on the Red Sea, a government source says
Perim Island divides the Bab al-Mandab Strait, the southern gateway to a trade route that links Asia and Europe - here's why it is significant
The Houthis' lightning advance appears to have taken most observers by surprise, says the BBC's Paul Adams
The Houthis have said they pose no threat to international shipping but have reiterated their threat to target vessels from Saudi Arabia
A spokesman says they will announce details of a "large-scale military operation"
Saudi Arabia has relied on the Red Sea for oil exports since the US and Israel's war effectively closed the Strait of Hormuz
At least 46,000 people have been displaced in Yemen since fighting escalated last week, according to the International Organization for Migration
We've just recieved an expected update from the Houthi's military spokesman.
It doesn't appear to mention the events that have unfolded over the past couple of days - we'll bring you a fuller look at the statement in just a moment.
Paul Adams
Diplomatic correspondent
The Houthis' lightning advance across the southern reaches of the Tihama – Yemen's arid coastal plain – appears to have taken most observers by surprise.
Until recently, the anti-Houthi coalition, known as the National Resistance, held significant territory along Yemen's Red Sea coast. In a matter of days, much of this has fallen to the Houthis, who are enjoying their most significant battlefield gains for years.
But Hisham al-Omeisi, a Washington-based analyst at the European Institute of Peace, says the latest developments are far from surprising.
"The National Resistance forces have been warning… for a while," he tells BBC News, "and unfortunately the international community has been dragging its feet."
"Now that they are there [in Mocha, the Red Sea port city], they're going to be entrenched and it’s going to be a lot more costly to push them out.”
Some see the sudden collapse as an inevitable consequence of a lack of coordination and sporadic infighting among anti-Houthi forces, as well as deep divisions between Saudi Arabia and the United Arab Emirates, who once formed the backbone of the international coalition supporting Yemen's internationally-recognised government.
The US is in "regular communication" with regional allies regarding Yemen and "remains focussed" on its "counterterrorism goals against the Houthis", a US State Department spokesperson tells the BBC.
"The United States' core interests in the Middle East include ensuring freedom of navigation in the Red Sea and the region, as well as preventing the export of terrorism," the statement reads.
It adds that the Trump administration has "clearly demonstrated its commitment to defending these interests against aggression from Iran and its proxies".
The State Department did not comment specifically on the latest advance of the Iran-backed Houthis against key Yemeni port sites on the Red Sea.
Paul Adams
Diplomatic correspondent
The latest Houthi advances in Yemen's remote southwest don't just represent a significant development in the course of Yemen's long civil war but also threaten one of the world's most important maritime waterways.
By capturing the small southern port of Mocha and reportedly occupying strategic islands in the southern Red Sea, the Houthis appear to be in a position to control the flow of shipping through the vital Bab al-Mandab strait.
The Iranian-backed rebels, who control much of Yemen's north, including the capital Sanaa, say they will only target Saudi-linked ships, but their record in attacking a wide range of international vessels in response to Israel's war in Gaza will make all nations using the Red Sea extremely nervous.
To the north, satellite images suggesting that Houthi missiles and drones struck Saudi Arabia’s East-West pipeline – a vital alternative route for Saudi oil exports following the closure of the Strait of Hormuz earlier this year – points to an effort by Iran’s Yemeni allies to add to the economic pressures generated by the US-Israeli war with Iran.
With the Strait of Hormuz still mostly closed, the possibility that the Bab al-Mandab might experience a similar fate is a real worry.
By Shruti Menon, Thomas Spencer and Peter Mwai
BBC Verify has been examining material which shows fighters inside the key Red Sea port city of Mokha yesterday after it was captured by the Houthis.
One verified image shared on Telegram shows four armed men outside the Mohka airport terminal building, which is on the coast, just south of the main sea port.
Image source, TelegramOne video also shows armed men driving along one of the main roads in the centre of Mokha on four pick-up trucks.
In the clip, a man can be heard shouting a well-known Houthi slogan.
Image source, XHouthi rebels have "taken control" of Perim Island in the Bab al-Mandab Strait, according to a source. Earlier, we were reporting that the group had reached the key island.
The AFP news agency also says Houthis have "taken over" Perim Island, also referred to as Mayyun, according to eyewitnesses and a local government official.
"Boats carrying armed Houthi fighters reached Mayyun Island after government forces withdrew from it yesterday," the official tells AFP.
Jonathan Josephs
BBC business reporter
These latest escalations are likely to further squeeze global energy supplies in a week where the price of oil has already surged past $100 a barrel.
It’s the first time that has happened since late July, and that reflects traders concerns that Saudi Arabian oil supplies have fallen sharply.
With the world's second biggest oil producer under renewed attack from the Houthis there could be yet more pressure on those supplies.
Different figures for Saudi oil production have been published by in the last 24 hours but both show a big drop in August compared to July.
The International Energy Agency says it fell from 8.24 million, external barrels per day (bpd) to 5.97 million bpd, whereas Saudi government figures published by the Organization of the Petroleum Exporting Countries (OPEC) suggest the drop was from 8.14 million, external bpd to 6.24 million bpd.
Either way, the reduction is significant and it means production is heavily down on the same time last year.
Meanwhile, supplies via the Strait of Hormuz also remain reduced and President Trump’s suggestion that the US Iran conflict won't be over for some time means there is little prospect of that changing.
These higher energy prices continue to stoke inflation around the world which is putting pressure on central banks to increase interest rates as the European Central Bank did yesterday.
The chances of the US and Japan following suit next week are growing and the fear is that will weigh down economic growth.
By Paul Brown
Satellite imagery indicates there were several fires yesterday along a 68 mile (109km) stretch of Saudi Arabia's Abqaiq-Yanbu oil pipeline, which connects the Gulf and Red Sea.
European Space Agency imagery examined by BBC Verify shows a large plume of black smoke emanating from the vicinity of pumping station about 45 miles (72km) south of Medina.
Image source, Sentinel-2, CopernicusData from Nasa's fire-detection software FIRMS also show heat anomalies at eight points along the pipeline at around 17:00 BST yesterday.
One of these heat signatures is located at the same pumping station.
Image source, Nasa FIRMSThe pipeline is used by Saudi Arabia as an alternative to exporting via the Strait of Hormuz, which has been severely disrupted since the outbreak of the US-Israel war with Iran in February.
It is not possible to say what the exact cause of the smoke plume was, or how much damage has been caused, from the satellite images.
But experts on social media say, in the event of damage to a pipeline, safety systems are in place to close valves and redirect the pipeline's contents within a damaged section to burn off as flares to reduce further impact.
This could mean the multiple heat signatures are the result of these safety measures triggered by a single point of damage.
Following the effective closure of the Strait of Hormuz for large periods of the US-Iran war, Saudi Arabia turned to its east-west pipeline to transport oil exports to the Red Sea.
Earlier this year Saudi Arabia was diverting as much at 70% of its crude exports from the Gulf to its Red Sea port of Yanbu through the pipeline.
Through this pipeline, the Saudis have been able to ship oil to Asia travelling south through the Red Sea's Bab al-Mandab Strait.
However, with the Houthis reportedly reaching Perim Island, that divides the strait, Saudi oil exports could be impacted.
The Houthis say they pose no threat to international shipping, except for vessels from Saudi Arabia.
Katy Watson
Reporting from Jerusalem
Yemen has been locked in a civil war since 2014 when the Houthi movement, which has links with Iran, took the capital Sanaa.
It’s caused one of the worst humanitarian crises in the world – thousands have died and nearly five million have been displaced, with many facing starvation.
The roots of the conflict started in the Arab Spring of 2011 – an uprising forced the country's long-time authoritarian president, Ali Abdullah Saleh, to hand over power to his deputy, Abdrabbuh Mansour Hadi.
But the political transition was anything but smooth and the Houthis took advantage of Hadi’s weakness and toppled his government
In March 2015, Saudi Arabia led air strikes against the Houthis, intending to restore Hadi to power.
The Saudi-led coalition was worried that if the Houthis' influence would empower their rival regional power Iran, in Yemen.
By 2022, a UN-brokered ceasefire was agreed – but it’s come under huge strain this year with the war in Iran breaking out.
Peace has become fragile once again – the Houthis know they will have leverage over the US if they can control the Red Sea
Houthi military spokesman Yahya Sarea says a statement is expected - but does not provide more details about when.
In a post on Telegram, he says the group will announce "a large-scale, high-impact military operation".
Katy Watson
Reporting from Jerusalem
This reported move is significant – and would put the Houthis in control of a key island that divides the Bab al-Mandab Strait in two.
Perim sits at the narrowest point of the strait – in the middle of a shipping lane that’s become increasingly important since the Iran war began.
With the effective closure of the Strait of Hormuz – a route that accounts for a fifth of the world’s oil supply – Saudi Arabia has had to reroute much of its oil through the East-West pipeline that connects to the Red Sea.
Houthi officials say Red Sea navigation is safe for all shipping companies except for Saudi vessels, pushing up the tension as well as oil prices.
If the Houthis gain control of this waterway, that will put Iran at an advantage and risks further reducing oil supplies which have risen to above $100 a barrel.
The Bab al-Mandab Strait is the southern gateway to a key shipping route that links Asia and Europe via the Red Sea and Suez canal.
Since the US and Israel's war effectively closed the Strait of Hormuz in the Gulf, Saudi Arabia has relied on the Red Sea for oil exports.
The Saudis have been able to ship oil in bulk to customers in Asia using tankers that depart south, past Yemen and the Bab al-Mandab Strait, and out into the open Indian Ocean – but this is now at risk as the Houthis threaten vessels passing by their coast.
The escalation of the conflict between the Houthis, Yemen's government and Saudi Arabia has contributed to a surge in oil prices.
Image source, Getty ImagesAt least 46,000 people have been displaced in Yemen since fighting escalated last week, the International Organization for Migration (IOM) says.
In an update released today, the IOM adds the "number is alarmingly rising by the hour".
"Families are being forced to flee for the second or third time in this conflict, with almost nothing left," said Amy Pope, IOM Director General.
The latest news comes a day after the Houthis seized the strategic Red Sea port city of Mokha from Saudi-backed pro-government forces, according to military sources and witnesses.
The Houthis said they posed no threat to international shipping but have reiterated their threat to target vessels from Saudi Arabia.
The kingdom has relied on the Red Sea for oil exports since the US and Israel's war effectively closed the Strait of Hormuz in the Gulf.
Yemen's Houthis have reportedly reached Perim Island - an important maritime chokepoint at the mouth of the Red Sea.
The island divides the Bab al-Mandab strait, the southern gateway to a trade route that links Asia and Europe.
Yemeni government forces have, according to officials, withdrawn from the island.
There has been no immediate confirmation from the Houthis that they have reached Perim Island.
