DUBAI/CAIRO — Yemen’s Iran-aligned Houthi movement announced a naval blockade against Saudi Arabia on Monday, opening a new front in the expanding US-Iran war and extending the threat to global energy supplies and trade beyond the Gulf.

The Houthis said they were imposing an immediate ban on Saudi maritime navigation under what they called a policy of “blockade for blockade.”

The group described the measure as retaliation for what it called Saudi Arabia’s nearly 12-year blockade of Yemen, accusing Riyadh of restricting the country’s ports and airports and depriving Yemenis of their resources.

Saudi Arabia has not yet publicly responded to the announcement.

Reuters previously reported that Iran had urged the Houthis to prepare to close the Bab al-Mandab Strait, the southern gateway to the Red Sea, if the United States continued attacking Iranian energy infrastructure.

A complete closure of the strategic waterway could reduce global oil supplies by as much as 7%, while forcing commercial vessels to take the longer and more expensive route around South Africa’s Cape of Good Hope.

The disruption would deepen an existing global supply shortage caused by the war in the Gulf, which has already reduced worldwide oil shipments by an estimated 10%.

Diplomatic efforts continue

The Houthi announcement came as Iran and the United States signalled an interest in reviving diplomatic efforts to halt the latest escalation, which has threatened to collapse a fragile interim agreement reached last month.

A senior Iranian official told Reuters that mediators had presented Tehran with a proposal for a 10-day ceasefire. The pause would be used to explore ways of reviving the interim agreement and opening negotiations toward a permanent end to the war.

The conflict began on February 28 with joint American-Israeli attacks on Iran.

Oil prices briefly climbed above $90 a barrel following renewed disruption to shipping through the Strait of Hormuz. The gains later eased after Iran’s Foreign Ministry confirmed that mediators had recently submitted proposals to Tehran, indicating that diplomatic contacts remained active.

Neither the ministry nor the senior Iranian official provided further details about the proposed ceasefire or identified all the parties involved in the mediation.

Two Pakistani government sources said Iranian Interior Minister Eskandar Momeni had asked Islamabad to resume its role as a mediator between Tehran and Washington. The request was reportedly made during Momeni’s second visit to Pakistan in less than a week.

The diplomatic activity followed another night of US strikes on Iranian cities. Iran’s Revolutionary Guards subsequently announced that they had targeted American military assets across the Middle East.

The Houthi blockade now raises the possibility of simultaneous disruption at the Strait of Hormuz and Bab al-Mandab—two of the world’s most important maritime routes—further increasing the risk that the war will spread across the region.