As the U.S.-Israeli war on Iran enters its second month, Tehran seems to have finally thrown its left hook.

Over the past weekend, the Iran-backed Houthi militants in Yemen joined the war (after weeks of threats to do so) with an ineffective missile attack on southern Israel. Experts warn that greater Houthi involvement in the war could upend already edgy energy markets and further strain a U.S. military gearing up for possible ground actions against Iran itself. The biggest threat is that the Houthis could reprise their previous attacks on shipping in the Red Sea, which has become the only safety valve for trapped oil flows that cannot leave the Persian Gulf.

As the U.S.-Israeli war on Iran enters its second month, Tehran seems to have finally thrown its left hook.

Over the past weekend, the Iran-backed Houthi militants in Yemen joined the war (after weeks of threats to do so) with an ineffective missile attack on southern Israel. Experts warn that greater Houthi involvement in the war could upend already edgy energy markets and further strain a U.S. military gearing up for possible ground actions against Iran itself. The biggest threat is that the Houthis could reprise their previous attacks on shipping in the Red Sea, which has become the only safety valve for trapped oil flows that cannot leave the Persian Gulf.

“Houthi involvement represents a significant and potentially dangerous development—even if it still carries a largely symbolic dimension at this stage,” said Maged al-Madhaji, the chairman and co-founder of the Sana’a Center for Strategic Studies, a think tank in Yemen. “If the risks facing Tehran escalate, the Houthis will significantly intensify their involvement, potentially moving to directly target the Bab el-Mandeb Strait and disrupt energy flows through the Red Sea.”

The question of eventual Houthi involvement has dogged the war since it began on Feb. 28. For years, Iran has backed, armed, and utilized the Houthis as a key proxy operating in the southern part of the Arabian Peninsula. Sometimes, the Houthis warred with neighboring Saudi Arabia, Iran’s regional rival. At other times, the Houthis leveraged their location to threaten shipping passing through the Bab el-Mandeb Strait, a narrow chokepoint between the Red Sea and the Arabian Sea, and the natural outlet for all ships transiting the Suez Canal. Between 2023 and 2025, during Israel’s war with Gaza, the Houthis all but shut down shipping in the Red Sea with sporadic attacks, despite an intense U.S. naval and air bombardment of Houthi positions.

But during this war, the Houthis have been strangely quiescent. In recent days, however, Houthi spokespeople have said that as Iran comes under increasing pressure—such as from the thousands of U.S. ground troops assembling in the region for a possible assault on Iranian territory—that the group may enter the fray.

The question now is whether the start of Houthi involvement is a harbinger of a double-pronged assault on the world’s energy flows or if it is just a way to placate the group’s one sponsor, Iran. 

Since 2022, the Houthis have shied away from direct confrontation with Saudi Arabia; despite a freeze in negotiations, Houthi officials still hope that Riyadh will provide financial support for the rump state that the Houthis control in northwestern Yemen. But Iran’s siren call beckons louder.

“Ultimately, in decisive moments, the Houthis are more likely to align with their primary strategic partner in Tehran, given Iran’s central role in their political, military, and security development, as well as their broader ideological convergence,” Madhaji said. “Targeting Saudi assets, oil tankers, or even international shipping is a plausible next step on the escalation ladder, particularly if the United States takes major actions such as striking Iranian energy infrastructure, forcibly controlling or reopening the Strait of Hormuz, or targeting key sites like Kharg Island.”

U.S. President Donald Trump threatened precisely that in a social media post on Monday. “Great progress has been made but, if for any reason a deal is not shortly reached, which it probably will be, and if the Hormuz Strait is not immediately ‘Open for Business,’ we will conclude our lovely ‘stay’ in Iran by blowing up and completely obliterating all of their Electric Generating Plants, Oil Wells and Kharg Island (and possibly all desalinization plants!), which we have purposefully not yet ‘touched.’”  

While the Houthis have been absent in the Iran war over the past month, the group has not been passive on its homefront. The Middle East Forum noted that the Houthis have been aggressively moving toward rival-held territory on the southwest coast, which, if occupied, would give them high ground and choice launching spots for further attacks on the Bab el-Mandeb Strait. The Houthis did not undertake such coastal incursions even during their two-year campaign against Red Sea shipping.

Greater Houthi involvement, and especially the threat to the Bab el-Mandeb, is so worrisome because that strait has been the one outlet untouched by Iran’s otherwise solid chokehold on the Strait of Hormuz. 

Since the start of the latest Iran war, Saudi Arabia, the region’s biggest oil producer, has rerouted close to 5 million barrels a day—half its production—across the peninsula to oil terminals on the Red Sea. That means that the Hormuz crisis has only trapped 10 million barrels of oil a day, instead of the full 15 million barrels a day. If the Houthis go all in, virtually no more tankers will go to Asian economies already struggling with an energy crisis. Even the threat of going all in could terrify shippers and spike oil prices well beyond the current $115 a barrel.

“The Houthis do not necessarily need to shut down Bab el-Mandeb to affect energy markets,” Madhaji said. “Even limited or intermittent disruptions in the Red Sea could have outsized effects on energy markets, particularly given how sensitive current conditions already are.”

More than a month into the war, U.S. objectives remain unfulfilled, potential missions are proliferating, and enemies are multiplying, along with the challenges they pose. For the Trump administration, finding a way to restore and ensure the free flow of energy has gone from a sideshow to the only show—but there is no solution in sight.