SANA'A, July 20 — Yemen's Iran-aligned Houthis announced on Monday that they will impose a maritime blockade on Saudi Arabia, further throttling a global energy market already greatly restricted by Iran's closure of the Strait of Hormuz.
This is why it matters and what it means for the Iran war and the global energy crisis:
How big is the risk to global energy markets?
It is not clear how the Houthis would carry out a maritime blockade of Saudi Arabia, its northern neighbour along the Red Sea coast, or whether it would include a return to attacks on shipping.
Yemen sits on the Bab el-Mandeb strait — the southern gateway to the Red Sea — and closing that would open up a new front in the energy crisis and Iran's overarching conflict with the United States (US).
With Hormuz already disrupted, the Red Sea has become a critical alternative outlet for Gulf oil and other products. A serious disruption would mean both of the Middle East's major oil export routes are shut simultaneously.
Iran's partial blockade of the Strait of Hormuz after Israel and the US attacked it on February 28 disrupted most oil and other exports from the Gulf, raising prices and delivering a global energy shock.
Saudi Arabia responded by diverting more than 70 per cent of its normal daily crude exports to the Red Sea port of Yanbu. Ships from Yanbu bound for Europe go north through the Suez Canal. Those heading to Asia go south through Bab el-Mandeb.
Kpler and Signal Ocean data have revealed that shipments from Yanbu averaged four million barrels per day (bpd) in recent weeks, up from around 973,000 bpd a year earlier.
Total petroleum volumes transiting Bab el-Mandeb amounted to 7.4 million bpd in June, or about seven per cent of global oil output, up from 4.2 million bpd last year.
That has provided a lifeline for the energy market, helping to keep global oil prices down. Last week, Reuters reported that Saudi Arabia is considering an expansion of its crude oil pipeline to the Red Sea coast.
When the Houthis launched attacks on Red Sea shipping in November 2023, Gulf oil exports were flowing freely.
Who are the Houthis and are they closing Red Sea energy routes on behalf of Iran?
The Houthis emerged as a military, political, and religious movement in north Yemen in the 1990s, fighting guerrilla wars against the government in Sana'a.
They have been in a civil war against the Saudi-backed, internationally recognised government for more than a decade and have attacked Gulf neighbours with missiles and drones.
However, a 2022 truce between the country's warring sides largely held until last week, when Yemen's internationally recognised government said it had struck Sana'a Airport to stop an Iranian plane landing.
The Houthis said Saudi Arabia was responsible and in response fired missiles at Abha Airport in the kingdom's mountainous southwest.
A senior Houthi official, politburo member Mohammad al-Farah, then warned in an interview on Iran's Press TV website that if the situation kept escalating, Bab el-Mandeb would be closed.
Iran champions the Houthis as part of its regional 'Axis of Resistance', which includes Lebanon's Hezbollah and Iraqi Shi'ite militias, though its ties with the Yemeni movement are less clear than with those other groups.
The Houthis do not recognise Iran's Supreme Leader as their ultimate religious authority in the same way Hezbollah and the Iraqi groups do. Their motivations are mainly domestic, though the group is ideologically aligned with Iran.
The US says Iran has armed, funded, and trained the Houthis with help from Hezbollah. The Houthis deny being an Iranian proxy and say they develop their own weapons.
It is not clear how far the group's stance on Bab el-Mandeb and the Red Sea stems from its own strategic priorities or is being made on Iran's behalf.
What happened when the Houthis attacked Red Sea ships before?
After the October 7, 2023 Hamas attack on Israel and Israel's devastating campaign in Gaza, the Houthis began firing at Israel and on shipping in the Red Sea, saying they were doing so in support of Palestinians.
The attacks severely disrupted global shipping, prompting Maersk, Hapag-Lloyd, and other major companies to divert around Africa — a far longer, more expensive route.
Suez Canal Authority data indicated that the Red Sea traffic has not recovered since, with traffic through the Suez Canal down 52 per cent in 2025 versus 2023 levels and at its lowest in at least 50 years.
A US-led mission to restore free navigation in the Red Sea involved repeated strikes on Houthi targets and a defensive campaign that shot down hundreds of drones and missiles.
But some Houthi attacks continued until last summer, only ending completely with the Gaza ceasefire in October.
Last month, the Houthis said they would ban ships linked to Israel from the Red Sea after Israel renewed military attacks on Iran.
However, that threat was never carried out, and shipping groups Maersk and Hapag-Lloyd are resuming some Red Sea routes they had abandoned during the Houthi attacks last year.
What have they done during the latest Iran war?
While Hezbollah and the Iraqi groups joined the war early with rocket and drone fire after the first US and Israeli strikes on Iran, the Houthis had been comparatively quiet.
The group's leader Abdul Malik al-Houthi said on March 5: "Our fingers are on the trigger at any moment should developments warrant it".
Iranian commanders have repeatedly warned that the Houthis could join the war. The Houthis launched a few missile and drone attacks on Israel in late March and early April.
Revolutionary Guards Quds Force commander Esmaeil Qaani said on June 1 that they could choke off the Red Sea.
That may now have changed with their announcement of the blockade on Monday against what they called the "criminal" Saudi Arabia in retaliation for what they called the kingdom's siege of its ports and airports, including with last week's strike.
