Reports, including one in the Wall Street Journal, say Iranian Mahan Air flights ferried IRGC officers, drone parts, missile guidance systems and impact detonators to the Houthis, and that Guard officers directed attacks from front lines. The support reportedly contributed to a September offensive that gave the Houthis control of Yemen's Red Sea coastline and the strategically important Bab al-Mandeb strait, the narrow waterway linking the Gulf of Aden and the Red Sea.
The attacks have already inflicted casualties: a Houthi strike on King Khalid International Airport in Riyadh killed 13 people, and Saudi energy facilities and oil tankers have also been targeted.
Major-General Turki al-Maliki, spokesperson for the Saudi-led coalition backing Yemen's internationally recognised government, confirmed that an external state actor is behind the Houthis' arsenal, but did not name it. He said regional assistance had made the Houthis the first nonstate armed group to deploy ballistic missiles, offensive and suicide drones, and explosive-laden high-speed boats.
Iran and the Houthis deny the allegations, and the Houthis insist they are independent of Tehran, though the two are ideologically aligned.
Analysts said the reports confirmed what had long been suspected. Ibrahim Jalal, a Yemen-focused analyst, said Revolutionary Guard and Hezbollah experts had managed operational planning in battles against the Yemeni government and neighbouring countries, citing the 2021 killing of Hassan Irloo, the Guard's envoy to the Houthis. Ali al-Dahab, a military and security affairs expert, said the reports added detail on a new smuggling method: small submarines carrying precision technologies for missiles and drones, where smugglers previously used traditional dhows.
Al-Dahab warned of broader implications for international shipping, saying the Houthis now serve as Iran's supporting force in the Bab al-Mandeb, and raised the prospect of Iran-aligned groups in the southern Red Sea uniting against the United States, Britain and Europe.
The allegations also test the détente Saudi Arabia and Iran reached through a China-brokered agreement in Beijing in 2023. Hesham Alghannam of the Carnegie Endowment for International Peace said he doubted Riyadh ever read the agreement as reconciliation, rather than as a way of lowering tensions. "It's keeping two files apart, and it works until someone says it out loud. That's what's changed," he said. "The deeper question was never whether Tehran signs. It's whether anything Tehran signs reaches the people holding the launchers."
Alghannam recalled that the Houthis were offered seats and a share of executive authority in 2014 in return for handing heavy weapons to the state, only to seize the capital, Sanaa, and detain the president. Former president Ali Abdullah Saleh, who partnered with them, was killed in 2017. "The Saudi red line is one thing, no armed group or second army inside one state," he said.
The Saudi-led intervention that began in March 2015 has failed to retake Sanaa, exposing divisions between the recognised government and southern separatists.