Last week, in a shock offensive, the Yemeni rebel group known as the Houthis seized territory near the Red Sea’s strategic Bab el-Mandeb Strait. In doing so, they opened a volatile new front in the destabilizing war between the United States and Iran, and left Saudi Arabia, an old enemy of the rebels, searching for allies and scrambling for a response. Various military advances by the Houthis have rocked Yemen since 2014. That year, the group, whose official name is Ansar Allah, surged to prominence by capturing Sana’a, the country’s capital, a swaggering first step in their evolution from a scruffy militia to the rulers of large swaths of Yemeni territory. This led to more than a decade of conflict with a disparate band of Yemeni opponents, along with Saudi Arabia. Still, nothing in the war has seemed as startling or as consequential as their breakneck assault last week, which centered on the capture of Mokha, a major port city on the Red Sea, and Perim, a tiny island at the southern entrance to the waterway. Both locations put the Houthis within firing distance of any ships that attempt to traverse the narrow strait. The rebels now control Yemen’s entire Red Sea coastline.

In the path of the offensive, opposing forces—primarily trained, equipped, and supported by Saudi Arabia and the U.A.E.—seemed to melt away. “The result is catastrophic,” Amr al-Bidh, a senior official with Yemen’s Southern Transitional Council, a separatist group that has clashed with the Houthis, told me. “It’s created all these alarms.” Not only had war returned to Yemen but uncertainty had fallen over the Red Sea, which has served as a reliable alternative route for oil shipments in the Persian Gulf since Iran began blockading the Strait of Hormuz, the entrance to the gulf, earlier this year. In March, Saudi Arabia, because of the shipping restrictions in the Persian Gulf, began transporting its crude oil through a pipeline that stretches from the kingdom’s Eastern Province to the Red Sea port of Yanbu, on its western coast. Fears that Iran and its close ally, the Houthis, effectively control two of the world’s most important maritime choke points rattled global energy markets. Then, last week, a drone attack that Saudi Arabia said was launched by Iran-backed militias inside Iraq hit the pipeline, causing a spike in the price of a barrel of Brent crude oil, a global benchmark in the oil markets.

Houthi officials tried to assuage fears about their intentions. Though they had previously announced a maritime blockade on Saudi Arabia, passage through the Red Sea remained “safe and orderly,” a Houthi spokesman, Mohammed Abdulsalam, said in a post on X on September 10th. The strait and the Red Sea faced “no danger” from the Yemeni side. But widely shared videos on social media showed that the rebels were also celebrating, hailing their offensive as a blow against foreign intervention and a strategic milestone that could tip the balance of Yemen’s once stalemated war. “The American-Saudi project aimed at regionalizing and fragmenting Yemen has been brought down,” a commentator wrote in Saba, a Houthi-run news agency. Control over the Bab el-Mandeb Strait would serve “Yemeni national interests” and “Arab and Islamic national security.”

The United States, which last year carried out a nearly two-month-long military campaign against the Houthis that left them battered but hardly vanquished, has signalled that it might accommodate the rebels this time around. Reuters reported that American officials met with Houthi representatives in Oman last weekend, and were told that there would be no attacks on American ships in the Red Sea. President Donald Trump, speaking to reporters last Saturday, seemed less than alarmed by the group’s success. The Houthis “called us and they don’t want to fight with us,” he said. “They don’t want us to go after them.” There was “one country,” Trump added, that the Houthis were “not too happy with”—an apparent reference to Saudi Arabia. “We’ll get that straightened out,” Trump said.

Still, days later, there was no evidence that the Saudis and the Houthis were de-escalating, or that the United States, the kingdom’s defense partner, would immediately provide direct military support. Axios had reported that the Saudi Crown Prince, Mohammed bin Salman, had called Trump twice as the Houthis advanced, asking for U.S. air strikes against the rebels. Trump, who had signed what the White House called a “historic” defense agreement with the Saudis in November, 2025, declined. And few analysts expect Turkey and Pakistan, which also recently signed a joint-defense pact with the Saudis, to commit troops to Yemen. On Tuesday, Saudi Arabia called on the global community to present a unified front. “The security of maritime waterways is a collective responsibility that requires an active international partnership,” Abdulaziz Alwasil, the kingdom’s ambassador to the United Nations, said in an emergency Security Council Meeting on the crisis. Saudi Arabia, he added, had “left no stone unturned to help Yemen to realize peace, stability, and prosperity.”

Saudi Arabia, as its cities and oil installations have come under Houthi attacks, faces a reckoning in Yemen. For now, the kingdom is going at it alone, carrying out air strikes across Yemen to shore up its beleaguered allies on the ground, but, in another setback, Houthi media aired a video on Wednesday of what it said was a Saudi fighter jet the rebels had downed using a locally made missile.

Across Yemen, front lines are reigniting, not just on the coast, but further east, in the Taiz Province, and in the oil-rich province of Marib, in central Yemen, with battles leading to the deaths of hundreds, according to both the Houthis and their adversaries. Across the rugged landscape that has made Yemen famed for its beauty, videos of the fighting over the last few days showed men dying violently on craggy mountains and on barren desert flats. In a matter of days, at least a hundred thousand people had been displaced by the fighting, the United Nations refugee agency said. More than twenty-four hundred people in Yemen have boarded boats and fled across the Red Sea to Djibouti. “The optimistic side of me says there is always hope, there is always a way for diplomacy and a political settlement,” Ahmed Nagi, a senior analyst at the International Crisis Group who focusses on Yemen, said. But the Saudis, humiliated by their losses in Yemen, seem likely to lash out. And the Houthis, emboldened by their victories, are already digging in. “The situation in Yemen is moving from bad to worse,” he said.

The rebels’ capture of Sana’a in 2014 spurred a military intervention by a Saudi-led coalition of Arab states—with intelligence, logistical, and munitions support from the U.S.—which aimed to defeat the Houthis. Its architect was Mohammed bin Salman, now Saudi Arabia’s de-facto leader, who, at the time, was serving as the defense minister. The Saudis, then mired in a regional cold war with Iran, viewed the Houthis as an Iranian proxy force that threatened the kingdom’s borders. Although the Houthis made no secret of their affinity for Iran—and their shared antipathy to Israel and the United States—the depth of their collaboration, for years, was a matter of debate, and the rebels were mostly seen to be acting in their own interests.

At the time, Yemen was divided by battle lines and ruled by feuding authorities: the Houthis in the north, and in the south the government that the rebels had expelled from Sana’a. Neither was capable of providing for citizens made desperate by endless war and endemic poverty, who were often left to fend for themselves. Meanwhile, the southern government enjoyed international recognition but was heavily under the sway of its Saudi backers. Years passed, and the Saudi-led coalition made little headway against the Houthis. Instead, their effort became known for a reckless and deadly air campaign that routinely killed civilians—including at weddings, at funerals, and in the factories where they worked. The strikes were often most vicious in the far north of Yemen, a rebel stronghold and the region where the Houthi movement had been founded, in the nineteen-nineties. The war immiserated Yemen. As a Saudi-imposed air and sea blockade contributed to disease outbreaks and famine-like conditions, the Houthis laid siege to cities and built a fiercely insular and repressive state, jailing critics and humanitarian workers. Then, in 2021, after years of criticism for its association with the Saudi war effort, the United States announced that it was ending all “support for offensive operations.” A United Nations-brokered truce the following year gave Yemen a period of relative calm.

The country did not stay quiet for long. In 2023, at the start of the war in Gaza, the Houthis, still in control of the most populated areas in Yemen, began attacking ships in the Red Sea, in solidarity, they said, with Palestinians. In 2025, during the American campaign against the Houthis, the U.S. military said that air strikes hit hundreds of targets, including weapons depots and air-defense systems. A tally by the nonprofit watchdog Airwars found that the campaign killed at least two hundred and twenty-four civilians. By the time that the United States and Israel attacked Iran in February, there was an “interconnectedness between the Houthi strategy and the Iranian strategy,” Nagi said. The Houthis saw the attack as a blow not simply against Tehran but against “the whole of Axis of Resistance,” the constellation of Iranian-allied militias around the region, including in Lebanon and Iraq.

As the Houthis and Iran grew closer, another wartime partnership in Yemen, between Saudi Arabia and the United Arab Emirates, was falling apart. The two Gulf powers—friends in the best of times but more often rivals—fell out spectacularly after Emirati-supported forces in Yemen, late last year, seized territory in two eastern provinces, including areas controlled by Saudi-backed groups. The U.A.E. announced that it was withdrawing its remaining troops in the country after the Saudis bombed an Emirati arms shipment bound for Yemen. Then, in July, whatever remained of the truce between the Saudis and the Houthis collapsed, after the Saudis, who control Yemen’s airspace, refused to let an Iranian airliner land at the airport in Sana’a. (The plane landed in the Houthi-controlled port city of Hodeida instead.) “It was the spark of this crisis,” Nagi explained. And, as the conflict escalated, he said, the Houthis had to choose where to send their fighters next. One obvious option was the province of Marib, which, with its oil wealth, would give the rebels a powerful card to play as they sought concessions in any future negotiations with the Saudis and their allies in Yemen. Instead, they went to the coast, where their interests in controlling a major shipping bottleneck dovetailed with those of Iran. When the rebels barrelled south, they found they were pushing at a nearly open door.

As the Houthis approached the Red Sea, the area was defended by several armed formations that were nominally controlled by the Saudis. But it was quickly apparent that there was mistrust among the groups, which answered to different commanders and lacked the supervision of a unified operations room. I spoke with a Yemeni official, part of the internationally recognized government in the south, who described the groups as “nonstate actors, within the state, but not controlled by the state.”

For months before the advance, the Houthis had been carrying out ballistic-missile attacks and drone strikes in the region, bombing the port in Mokha to make sure that their Saudi-backed adversaries did not receive support from the sea, and advancing westward from Taiz to control the mountains overlooking the port. Early last week, Tareq Saleh, the commander of one of the most prominent anti-Houthi formations, the National Resistance, complained that the situation was getting worse and that he was receiving little support, the Yemeni official told me. “It was clear his lines of defense were failing,” the official said.

Anti-Houthi soldiers began to see other allied forces retreating, and they assumed that the withdrawing fighters had “received better intelligence from their leadership, to leave,” Nagi told me. “Then you had this domino effect. Can you imagine, sixty thousand soldiers just running to save their lives?” There were reports, too, that the Houthis compromised the communications systems of their enemies and issued fraudulent orders to retreat.

Many observers believe that the battle might have unfolded differently if the Emiratis were still involved in Yemen. Emirati forces had been instrumental during several major operations during the civil war, helping to repel a Houthi advance on the southern city of Aden, and expelling Al Qaeda, which has had a presence in Yemen for decades, from the southern port city of Mukalla. “They are more aggressive. They are more disciplined. They don’t hesitate,” the senior Yemeni official said, comparing the Emiratis with Saudi forces. “When they go to war, they are physically present. That’s the difference.”

But, for others, the crisis has been a warning about the ways Yemen has fallen captive to foreign states—whether the Saudis, the Emiratis, or Iran—that make decisions about when to escalate the war, how to prosecute it, and the compromises that Yemenis should be willing to accept to end the conflict. “The Yemenis lost their local agency,” Maysaa Shuja al-Din, a senior researcher at the Sana’a Center, a think tank based in Aden, told me. The war “started as a local conflict with local roots and started to become more regional.” As a result of years of interference, she said, many in the country have become increasingly hungry for more independent, homegrown leaders.

For now, it is likely that the Houthis will use their recent victories, and their newfound leverage in the Red Sea, to escalate their demands in any peace negotiations, she told me. In the past, the rebels have demanded the payment of public-sector wages in their areas using Yemen’s collective oil revenues, and that Saudi Arabia compensate the rebels for the war. Given the always shifting nature of the front lines in Yemen’s conflict, in addition to those across the region, the Houthis’ control of Bab el-Mandeb was likely “transitional,” the Yemeni official said. In any case, he said, the Houthis “want to bargain for something else.” ♦