Iran-aligned Houthis seized control of Yemen’s port city of Mocha on Thursday and advanced down the Red Sea coast to strategic islands, military sources said, hours after President Donald Trump said he expected the Iran war to end after the US midterm elections.

Yemeni government military sources said the Houthis had gained further leverage over the Bab el-Mandeb Strait, the southern ‌outlet of the Red Sea and one of the world’s most important shipping routes, and had reached the islands of Hanish.

If the Houthis were to gain control of the waterway on the opposite side of the Arabian Peninsula from the Strait of Hormuz, it could give their backer Iran a critical advantage in the war with the United States, reducing supplies through a second major transit corridor and sending oil prices surging.

It could also make it harder for Trump to find an exit from a war that has hurt his Republican Party’s electoral prospects ahead of the November midterms.

Yemen’s Houthi-run humanitarian operations coordination centre said in a statement that Red Sea navigation is safe for all shipping companies except for Saudi vessels.

Saudi Arabia, the world’s largest oil exporter, has relied on the Red Sea route since the Iran conflict effectively closed Hormuz, through which a fifth of global oil used ⁠to flow.

Yemeni government forces and their allies are relocating south along the Red Sea coast to Dhubab on the Bab el-Mandeb Strait, across from Perim Island, government military sources said. Control of Dhubab and the island is key to gaining hold of the strait, they said.

U.N. Special Envoy for Yemen Hans Grundberg told a U.N. Security Council meeting about Yemen on Thursday that the international community must act to address “a new and more dangerous phase” in the Yemen war.

The Houthis’ gaining control of Mocha gave them “a direct presence on the approaches to one of the world’s most vital straits,” raising serious concerns about freedom of navigation, he said.

Jenifer Neidhart de Ortiz, the US representative at the meeting, accused the Houthis of acting as “agents and tools of Iran.”

“This escalation is unacceptable, and those who enable it bear responsibility for its consequences,” she said.

Iran’s foreign ministry said in a statement that the Yemen conflict could not be solved by blockade or military action against the Houthis and called for dialogue, without addressing Iran’s own role.

Yemeni government, Iranian and regional sources told Reuters the Houthi advance down the coast this week came with direct guidance from Iran’s Revolutionary Guard Corps.

Houthi spokesperson Mohammed Abdulsalam said, without elaborating, that the group’s operations were defensive and would stop once attacks on Yemen stopped.

Oil prices jump

Brent crude prices jumped as much as 4% on Thursday above $105 a barrel on concern over disruption to supply routes, and the ‌US national ⁠average price of diesel surpassed $6 a gallon for the first time ever, according to price tracker GasBuddy.

After joining the war with an attack on Israel in March, the Houthis declared a naval blockade against Saudi Arabia in July and escalated attacks this month.

Tensions in the region remained high, with Saudi civil defence authorities issuing emergency alerts in the southwestern city of Khamis Mushait for the fourth time in 24 hours, as the Houthis attacked.

Pakistan has delivered a Saudi warning to Iran to rein in the Houthis to try to prevent the crisis from spiralling, Saudi, Pakistani and Iranian sources said. A senior Iranian official said Tehran’s response was: “Iran does not control the Houthis”.

The fighting comes during the biggest declared wave of US-Iran tit-for-tat attacks on Gulf shipping since the war began in late ⁠February.

The US Treasury Department on Thursday announced new sanctions against firms and individuals aiding Hezbollah and other Iranian proxies as part of “Operation Economic Outcast,” which aims to cut off Tehran’s war funding.

Trump sees war ending after midterms

The war and subsequent increase in fuel prices have helped drive Trump’s popularity to record lows, according to polls. He said Iran was trying to influence the midterm elections, which will determine whether his Republican Party retains control of Congress.

“I don’t believe in the word ‘regret.’ You can always question yourself a little bit,” Trump ⁠said in an interview with Fox News host Laura Ingraham broadcast on Thursday, when asked if he regretted the Iran war due to the impact it may have on the elections. “If I had it do again, I would do exactly as I did,” he added.

Trump also reiterated his thinking that the war will end immediately after the midterm election, a comment he also made on Wednesday.

In recent weeks Washington had cited increasing success guiding tankers through the Strait of Hormuz, ⁠which carried about a fifth of global oil supplies before the war.

But a resumption of fighting this month appears to have set back any such gradual reopening. Just seven vessels transited the strait on Wednesday, half the 10-day average, preliminary ship-tracking data showed.

Iranian state media said on Thursday the Revolutionary Guards Navy had struck a US unmanned vessel at the entrance to Hormuz.