Saudi airstrikes hit the rebel-held Mokha airport in Yemen on Friday, an Iranian-backed Houthi broadcaster reported, one day after the Houthis entered the key Red Sea port city. The advance brought the group within 50 miles (80 kilometers) of the Bab el-Mandeb Strait, increasing concerns over commercial shipping on an important alternative to the Strait of Hormuz.

The Houthis’ entry into Mokha on Thursday was their biggest territorial gain in years against Saudi-backed Yemeni opponents. The city overlooks tanker routes out of the Red Sea, while Saudi Arabia has increasingly relied on the Red Sea and Bab el-Mandeb to export crude as Iran targets vessels in the Strait of Hormuz.

About 12% of the world’s goods are typically shipped through Bab el-Mandeb. Shipping through the strait had fallen by about 60% since the Houthis began attacking some vessels there in late 2023 while expressing solidarity with Palestinians in Gaza. Activity increased this year as Saudi Arabia sought alternatives to the Strait of Hormuz, but renewed Houthi threats have “curtailed” it, according to Lloyd’s List Intelligence.

The Houthis have increased attacks on Saudi shipping in Bab el-Mandeb and the Red Sea since declaring a blockade there in July, while also striking oil infrastructure inside Saudi Arabia. The group said its action responded to the kingdom’s yearslong blockade of Houthi-held areas of Yemen. Saudi Arabia has said it has the right to defend itself and earlier this week said it had always offered “opportunities for negotiation.”

Iran’s government on Friday called for an end to Saudi Arabia’s blockade of Yemen and for renewed negotiations between Saudi Arabia and the Houthis. Iran’s Foreign Minister Abbas Araghchi said the two countries’ foreign ministers spoke Thursday about diplomatic efforts to “restore stability” to the region. On Wednesday, the spokesperson for Iran’s Revolutionary Guard said any negotiated settlement with the United States should include Yemen, the first explicit reference to that front.

Experts said the capture of Mokha could support Iran’s strategy of raising world oil and gas prices to pressure the United States and could give Tehran more leverage in negotiations. Yemen’s Saudi-backed and internationally recognized government, meanwhile, strongly condemned renewed Houthi attacks on Saudi Arabia and called for international support as the rebels advanced along the Red Sea coast toward Bab el-Mandeb.