The true significance of the long-awaited entry of Yemen’s Houthis into the Iran war depends on whether the Tehran-backed proxy group is intending to send a few missiles and drones from a distance towards Israel or will instead capitalise on its proximity to the narrow Bab al-Mandab strait to effectively close off the Red Sea to shipping, just as Iran has in effect shut the strait of Hormuz.

The combined effect of both waterways being shut to commercial traffic from countries that neither the Iranians nor Houthis favour would be devastating. Napoleon Bonaparte’s remark that “the policy of a state lies in its geography” has never seemed more apt.

The Houthis, a Shia sect with a deep hatred of Israel that has run large tracts of Yemen including the capital since 2014, is a complex, resilient movement able to take reverses in its stride. In August 2025 Israel killed the Houthi prime minister, the chief of staff and a group of their cabinet ministers in a single intelligence-led strike. But Israel has never been able to locate Abdul Malik Al-Houthi, the movement’s leader.

It has not yet fought directly on behalf of Iran even though – according to UN reports – many of its arms have been shipped from Tehran.

A ceasefire with the US that emerged from mediation by Oman has been in force since May 2025, bringing to an end attacks on US shipping through Bab al-Mandab that had been taking place since October 2023.

That ceasefire reflected the damage the Houthis had sustained from successive waves of increasingly effective attacks on Houthi missile launchers by the US, sometimes with UK support. The Houthis stressed the ceasefire did not in any way shape or form apply to Israel and some attacks continued thereafter.

One motive for the ceasefire was an Iranian desire to build political momentum before US-Iran nuclear talks in spring 2025. The Houthis extended the ceasefire to Israel in October 2025 when Israel agreed a form of ceasefire with Hamas in Gaza. Even after the joint Israeli-US assault on Iran in the 12-day war last year, the Houthis largely held back.

But major carriers such as Maersk only slowly started to resume traffic through the Red Sea, avoiding the more expensive, significantly longer alternative route around the Cape of Good Hope.

The Bab al-Mandab, between Yemen and the Horn of Africa, has always been vulnerable to Houthis attacks by drones missiles and small boats.

Farea Al-Muslimi, Middle East specialist at the London thinktank Chatham House, warned any sustained disruption will drive up shipping costs, increase oil prices and place additional strain on an already fragile global economy reeling from the situation in the strait of Hormuz.

Iran’s broader strategy of activating allied groups across the region appears to be unfolding and he predicted that over time the perception inside Yemen that the Houthis are too attentive to Iran will grow.

The Houthis may act with caution, partly because they are looking for rewards in the form of cash from Saudi Arabia. In the south of Yemen, the Saudis have for the moment trounced the southern separatist cause, advanced by the Southern Transitional Council. The United Arab Emirates, which backed the STC at the turn of the year under pressure from Riyadh, has also left Yemen, meaning Saudi Arabia is now in sole charge of Yemen’s future – an onerous task that requires Riyadh to reach deals not just with the former STC supporters but also the Houthis.

The STC formally disbanded, but is still in existence and is waiting for Riyadh and the UN-recognised government in the south to fail, insisting the southern cause is as strong as ever. Riyadh cannot afford to fight on too many fronts, so if necessary it will try to find backdoor methods to strike a deal with the Houthis and minimise the threat of attacks in the Red Sea.

Saudi Arabia is pouring money into the new government in the south and the Houthis in the north may want a slice of the financial action in return for not resuming fighting against the south or disrupting the Red Sea.

However, in the end the Houthis’ power comes from interdicting ships as opposed to sending missiles towards Israel.

In the process Yemen could be left even further from peace after more than a decade of civil war.

The UN special envoy for Yemen, Hans Grundberg, said: “This escalation threatens to drag Yemen into the regional war, which will make resolving the conflict in Yemen more difficult, deepen its economic repercussions and prolong the suffering of civilians.” It is not his first warning against escalation, and it is unlikely to be his last.