Bab al-Mandab strait: Iran’s Houthi allies enter the conflict, raising fears over key trade route

Iran launched waves of missiles at Israel on Monday as Yemen's Iranian-backed Houthis carried out their second attack since the start of the US-Israeli war, with the Israeli military saying two drones launched from Yemen were intercepted early on the morning of March 30.

The Houthis entered the conflict for the first time two days earlier, firing missiles at Israel on Saturday in an escalation that has raised fears they could also move to disrupt shipping in the Red Sea, sending oil prices – already up more than 50 percent in a month – even higher.

Following the Strait of Hormuz in the Persian Gulf, Iran has repeatedly threatened to target the Bab al-Mandeb strait in the Gulf of Aden, south of the Red Sea.

"Insecurity in other straits, including the Bab al-Mandab Strait and the Red Sea, is one of the options" for resisting US threats, an Iranian military source told Tasnim, an Iranian news agency, on March 21.

A response to US threats

Iran will broaden its retaliatory measures if the United States or Israel were to launch a ground offensive in the region, Tasnim reported. Military retaliation still appears to be on the table, despite US President Donald Trump's calls for peace negotiations while Washington shows no sign of slowing its military build-up in the Middle East.

On Monday, Trump threatened to destroy Iran's main oil export terminal on Kharg Island and other energy infrastructure if Tehran does not agree to a deal.

Writing on his Truth Social network, Trump said the US is in "serious discussions" with "a more reasonable regime" in Tehran, but warned: "If for any reason a deal is not shortly reached ... we will conclude our lovely 'stay' in Iran by blowing up and completely obliterating all of their electric generating plants, oil wells and Kharg Island (and possibly all desalinization plants!), which we have purposefully not yet 'touched.'"

In an earlier interview with the Financial Times, Trump had already floated the idea of seizing the island and said that his preference was to "take the oil in Iran”. He also made a comparison with Venezuela, where Washington intends to control the oil industry following the capture of Nicolás Maduro in January. 

Faced with what Tehran perceives as a mounting threat, the Islamic Republic is considering an escalation that could include the closure of Bab al-Mandab with the involvement of the Houthis, who have so far been "surprisingly quiet", according to Natasha Lindstaedt, a specialist in authoritarian regimes and non-state actors at the University of Essex.

And the Iran-backed group is ideally placed to exert control over the strategic waterway.

The Houthis' “unique geographic position creates a unique ground for acting in the Red Sea and particularly at the level of the Bab al-Mandab strait", said Julian Pawlak, a maritime security specialist at the German Institute for International and Security Affairs (SWP) in Berlin.

A vital trade route

The Bab al-Mandab strait plays a key role in global trade as well as in delivering oil and gas to Europe.

"In normal times, around 15 percent of global maritime trade by value goes through it," said Jasper Verschuur, a professor of systems engineering and infrastructure security at Delft University in the Netherlands who has studied the cost of disruptions to strategic maritime routes.

The strait also plays a central role in moving oil and gas from the Gulf states to Europe. Tankers leave ports in the Persian Gulf, pass through the Strait of Hormuz, cross the Bab al-Mandab and then travel up the Red Sea to reach Europe via the Suez Canal. The passage at the southern end of the Red Sea is also heavily used by container ships carrying Asian goods destined for European markets, Verschuur said.

“Disrupting maritime traffic at the Strait of Hormuz primarily affects Asia, while blocking traffic in the Gulf of Aden is more likely to penalise Europe," said Didier Leroy, a researcher and specialist in Islamist movements in the Middle East at the Royal Higher Institute for Defence in Belgium.

The situation in the Middle East puts the importance of the Bab al-Mandeb into perspective according to Verschuur, especially since the number of tankers making their way from the Persian Gulf to the Red Sea via the Strait of Hormuz has already been significantly reduced.

Saudi Arabia has been able to reroute some of its oil exports to rely more heavily on the Red Sea. Via the East-West pipeline, Riyadh has been trying to supply Asia from its port of Yanbu on the Red Sea, passing through the Bab al-Mandeb strait.

If that route also becomes unsafe, "Saudi oil going to the East would need to take the route via Suez and Mediterranean, which will lengthen delivery times and push up prices even if the volumes of oil in question remain well below those affected by the closure of the Strait of Hormuz," said Christian Bueger, a maritime security specialist at the University of Copenhagen.

Traffic already 'cut in half'

Maritime traffic in the Bab al-Mandab strait had already fallen sharply, well before the current escalation in the Middle East. After the Hamas-led attacks of October 7, 2023, on Israel and the start of the war in Gaza, the Houthis regularly targeted vessels in the Red Sea.

"Before 2023, around 60 to 70 cargo ships passed through every day. Now we're talking about around half the number of ships," said Verschuur. Although the Houthis have been keeping a lower profile for nearly a year, he said most shipping companies had already been forced to make detours, notably through the Cape of Good Hope.

A closure of the Bab al-Mandab strait might therefore have less of an effect that it would have previously, but it would come at a time when traffic through the Strait of Hormuz is already very limited.

“The parallel action in the Strait of Hormuz and Bab el-Mandep would create big issues on how to deal with those disruptions and the flow of goods,” said Pawlak.

And the humanitarian consequences could be devastating. Forced to take longer routes, cargo ships will not be able to make as many voyages, which will mean "shipping companies may have to make choices, and maybe not serve some countries because it’s economically less profitable than the big routes", Verschuur warned.

The cheapest deliveries tend to involve essential goods, such as grain bound for poorer countries. "This could cause major disruptions in regional maritime trade, with impact on food security in the Horn of Africa," said Bueger.  

The Houthis, a 'strategic reserve'

The real question remains whether the Houthis want to block the strait on Iran's behalf. The group carried out a first attack on Israel on March 28 and a second on Monday.

"If they do it, it will be rather half-hearted," said Tim Epkenhans, a specialist on Iran and the Muslim world at the University of Freiburg.

Their restraint since the start of the war had, in fact, served both their own interests and those of Iran. On one hand, "the massive US strikes and the penetration of their organisation by Israeli intelligence services – which managed to decapitate part of their command structure – have cooled this armed group down", Leroy explained.

They also fear that "their involvement in the war would prolong the conflict – which runs counter to the interests of China, which prefers stability and a quick end to the conflict", and which has become an increasingly important partner for the Houthis, Epkenhans added.

Their reluctance to get involved does not particularly trouble Iran, for whom the Houthis represent "a strategic reserve, something like a last resort situation", Lindstaedt said.

Vincent Durac, a Yemen and Middle East specialist at University College Dublin, said the group's recent missile strikes on Israel could partly be a way of showing solidarity with Iranian interests, but "without really doing a whole lot".

He added that the timing might also reflect the Houthis' desire to underscore a regional standing they have only recently acquired.

"The Houthis have established a prominence that they simply did not have three years ago," he said. But any deeper escalation, particularly a move to disrupt shipping through the Bab al-Mandab, could carry serious risks for the group itself, Durac said.

"Yemen is overwhelmingly dependent on imports," he said. "Disrupting shipping, disrupting trade, isn't actually that great for the Yemeni economy."

The group has also taken note of what happened to the leadership of Hamas and Hezbollah.

"The ease with which the US and Israeli military, security and intelligence agencies have targeted their enemies in the region is not something they want to visit upon themselves willingly," Durac said.

Yemen's Houthi allies would have little difficulty blocking the Bab al-Mandab strait, at least initially. "It is a very narrow strait, less than 30 kilometres wide at one point which makes blocking operations easier," Lindstaedt said.

But while disrupting traffic could be relatively simple and quick, keeping the passage closed would be much harder, Pawlak said, and would mean “sustaining large-scale denial, and requires continuous effort”.

Given what is at stake, the military and diplomatic pressure on the Houthis would be enormous. Above all, Lindstaedt said, it remains unclear whether the group still has the financial and military means to sustain a blockade over the long term.

This article has been adapted from the original in French.