A group of rebels once known as Iran's "merchants of chaos" have moved on strategic islands in the Red Sea and are now putting one of the richest and most powerful nations in the Middle East in a tricky spot.
After a years-long stalemate, the Houthis reignited their war with Saudi Arabia and the internationally recognised government this year, launching a lightning assault in mid-September that ended in the capture of Mokha, a major port city, and the tiny island of Perim.
The seizure of the two critical areas gave the Houthis almost complete control of Yemen's Red Sea coastline, and put them within firing distance of any ships that attempted to navigate the Bab el-Mandeb Strait. (The Houthis had announced a blockade of ships carrying Saudi Arabian exports in July.)
"By taking the territory this simply allows [the Houthis] to harass shipping more easily and it also establishes them as the powerbroker in this critical waterway," said April Longley Alley, a Middle East analyst with the Washington Institute.
The Iran-aligned group were quick to act on their strategic advantage, firing at Saudi oil facilities on September 8 and tankers that attempted to navigate the narrow strait.
Days later an attack on Saudi Arabia's east-west pipeline, blamed on Iran-backed militias in Iraq, sent shockwaves through the Middle East and rattled world markets.
As economists and traders began unpicking the implications of the group's actions on the global economy, the Houthis took another step on their escalation ladder, launching strikes on critical infrastructure in Saudi Arabia.
Fuel tanks near the Saudi capital's international airport were targeted, as well as energy sites on the country's Red Sea coast.
Unlike many other nations, Saudi Arabia escaped the initial months of the war between Iran and the United States relatively unscathed. But analysts now fear the Houthis' growing assertiveness in the region could open a new, troubling front in the Middle Eastern conflict.
"It's monumental because Saudi Arabia was spared, and today Saudi Arabia will not be spared if the Houthis in Yemen are not reined in," Dr John Sfakianakis, chief economist at the Gulf Research Center in Riyadh, told ABC Radio.
Saudi Arabia is not the only nation vulnerable to the Houthis' tactics. Analysts warn the rebel group's actions in the Bab el-Mandeb Strait could also have a very real, and very troubling, impact on the prices consumers pay for oil and gas.
"It is damaging for everybody and nobody is spared from this," Dr Sfakianakis said.
As fighting has escalated in recent weeks, the Saudis looked to their allies, the United States, to intervene, as it did previously under the Biden administration and last year under Trump.
Crown Prince Mohammed bin Salman, the kingdom’s de facto leader and a major ally in the Iran war, even reportedly called the US President on September 17 to implore him for US assistance.
Over the weekend, Donald Trump came close to heeding those calls and ordering military strikes against the Houthis.
Military commanders were locked and loaded, holding approved target lists as troops loaded bombs onto aircraft selected for the operation, the New York Times reported.
But the planned strikes were called off at the 11th hour, according to the newspaper, with Mr Trump deciding there would be no US action "for now".
The President's decision now leaves him in a bind with the powerful kingdom and could have ramifications for the Iran war.
The Bab el-Mandeb Strait is a valuable prize
The Bab el-Mandeb Strait, known in Arabic as the Gate of Tears, sits between the Horn of Africa and the Middle East, and is the gateway to the Red Sea.
For millennia, this inlet facilitated local trade between Arabia and Africa, before expanding to international trade with the opening of the Suez Canal in 1869.
The narrow waterway now connects many of the Middle East's oil and commodity producers to the rest of the world, making it one of the busiest global maritime chokepoints.
When Iran moved on the Strait of Hormuz earlier this year, it exposed a key vulnerability in global shipping and forced many nations to look for alternate routes for their cargo.
The Bab el-Mandeb Strait became a "Plan B" export route during the Iran war, helping to cushion the impact of the effective closure of the Strait of Hormuz, particularly when it came to the oil-rich Saudi Arabia.
The kingdom started diverting a large amount of its exports away from the Strait of Hormuz into the East-West pipeline.
Built in the early 1980s, the 1,200 kilometre pipeline connects Saudi Arabia's Abqaiq oil processing facility in the east to the Red Sea port of Yanbu in the west.
From there, Saudi oil, which is mostly bound for Asia, is loaded onto tankers and carried out via two routes in the Red Sea. One is through the Suez Canal towards Europe, the other is through the Bab el-Mandeb Strait to the Gulf of Aden.
"During the course of the Iran war, Saudi Arabia has become more dependent on the Red Sea for the export of hydrocarbons they've exported through their East-West pipeline, through the port of Yanbu on the Red Sea coast," Ms Longley Alley said.
"And so the Houthis see an opportunity again to press their advantage with Saudi Arabia and to see if they get into war …on their terms."
'Difficult to get oil out'
Under the law of the sea, freedom of navigation in the world's strategic shipping channels is guaranteed.
That is how the Bab el-Mandeb Strait is supposed to operate. But just like with the Strait of Hormuz, this narrow passageway now appears to be beyond the bounds of international law.
"One of the things [the Houthis] demonstrated to the world, in effect almost teaching Iran or demonstrating to Iran, was that with the use of relatively cheap, relatively unsophisticated technology and weaponry … just the threat of that alone is enough to stop shipping," Timothy Walker, maritime researcher at the Institute for Security Studies in South Africa, told RN's Rear Vision.
During Israel's war with Gaza, the Houthis paralysed shipping through the Red Sea, killing at least nine sailors and sinking four ships.
Barrels of crude oil and petroleum liquids crossing the strait per day dropped from 9 million in 2023 to about 4.2 million barrels in 2025.
The US launched a bombing campaign against the Houthis in response and the two sides eventually reached a ceasefire deal, brokered by Oman, last year.
This time, the Houthis claim their actions in the Bab el-Mandeb Strait are a result of Saudi Arabia's own "unjust blockade on shipping traffic to and from Yemen".
The Houthis' endgame is complex and multifaceted but analysts said one of the group's desires is to see the end of all Saudi involvement or intervention in Yemen, including the kingdom's backing of the internationally recognised government.
"Saudi arrogance is unacceptable and the Saudi regime is an occupying power," Houthi leader Abdul Malik al-Houthi said in a televised speech on Monday.
Their actions also give Iran, which provides the Houthis with military support, another potential source of leverage as the United States loosens Tehran's grip on the Strait of Hormuz, on the other side of the Arabian Peninsula.
Analysts said renewed hostility in the Bab el-Mandeb Strait would very likely disrupt exports again, making it more difficult to get oil from the west coast of Saudi Arabia to Asia and Australia.
They warn that simply having the threat of disruption is very powerful because insurance companies become nervous about sending ships through the area and into harm's way. Diverting ships to other waterways then increases the cost of the journey.
"We have both straits [Hormuz and Bab el-Mandeb] under some kind of closure, and it's quite difficult to get product oil out," said Dr Sfakianakis.
Trump and Saudi Arabia in a tricky spot
The wealthy kingdom has been alert to the danger posed by the Houthis for some time.
The rebel group's seizure of Yemen's capital, Sanaa, in 2014, first sparked a war with the Yemeni government that spiralled into a Saudi-led bombing campaign to try to restore the latter to power.
It took almost a decade for a fragile truce to be reached between the two sides, but that agreement swiftly unravelled during the US-Israeli war with Iran. The pact officially broke in July when the Houthis declared a blockade on Saudi shipping in the Red Sea.
They then marched south to the coast, an area that happened to also be of strategic interest to their Iranian allies.
The group expected to meet resistance from several armed formations nominally controlled by the Saudis, but they reportedly managed to move in quickly after the soldiers retreated en masse.
Ahead of the group's capture of critical areas in the Red Sea, Crown Prince Mohammed reportedly called Mr Trump twice, urging him to launch strikes against the Houthis.
Axios reported that Mr Trump declined, and US officials had stressed at the time that the administration had no plans to intervene directly against the Houthis.
Potential US involvement now hangs over the conflict, with Saudi officials telling US media outlets the kingdom does not want to fight the Houthis alone
Saudi Arabia has turned to other countries, including France and Egypt, for help, but only the UK has agreed to provide defensive air support to the kingdom.
Saudi Arabia's tricky position comes just weeks after it signed a security pact with Turkey and Pakistan. This is the first test of the Mecca agreement but while the two nations have voiced support for the defence of Saudi Arabia, they have not entered the conflict yet
Meanwhile the Red Sea remains an active and evolving theatre in the Middle East conflict, a space where multiple actors are operating and may come into conflict at any moment.
