Iran’s Support of the Houthis: What to Know

Yemen’s Iran-aligned Houthi movement has become one of the Middle East’s most potent nonstate actors since Israel’s war against Hamas reignited in 2023. The group’s ability to maintain disruptive strikes in the Red Sea and the recent escalation in U.S. retaliatory attacks raise fresh questions about instability in the greater region.

Who are the Houthis?

The Houthis are a local rebel movement that currently rules a third of Yemen’s territory and two-thirds of its population. They revolted against the internationally recognized government in 2011 and overthrew it in 2014. Yemen’s civil war continues today, with its front lines largely frozen. The Houthis’ government, based in Yemen’s capital, Sanaa, is recognized only by Iran and is influenced by strict readings of Islamic law and local caste-based traditions. The Houthis’ infamous, Iranian-inspired rallying cry points to their ambitions beyond Yemen: “God is great, death to America, death to Israel, a curse upon the Jews, victory to Islam.” The United States designates them as a terrorist group.

The Houthis are formally known as Ansar Allah (Supporters of God in Arabic), but their popular name refers to the movement’s leaders, who come from northern Yemen’s Houthi tribe. Originally a political movement, the Houthis militarized in the late 2000s, fighting wars against Yemen’s government. They command some twenty thousand fighters, a mix of tribal forces and troops formerly loyal to the government. The Houthi movement is rooted in Zaidism, also known as “Fiver” Shiite Islam [PDF], meaning it recognizes only the first five of the Prophet Mohammed’s successors. It is practiced mainly in northern Yemen, where it has also taken on elements of Sunni Islam. Zaidis compose around a third of Yemen’s population of thirty-four million.

How did the Houthis become aligned with Iran?

By some experts’ estimations, Iranian military support to the Houthis began as early as 2009, amid the Houthis’ first war against Yemen’s government. Most experts agree that the Houthis were receiving weapons from Iran by 2014, the year they captured Sanaa. In both cases, military intervention against the Houthis by Iran’s regional rival, Saudi Arabia, likely catalyzed Tehran’s increased interest in the group.

Militant groups allied with Iran are frequently called Tehran’s proxies, but many experts say the Houthis are better characterized as Iran’s willing partner [PDF]. Iran’s model of “exporting” its 1979 Islamic Revolution by cultivating armed groups in the region allows these groups a degree of flexibility, the Washington Institute for Near East Policy’s Michael Knights told CFR. However, the Houthis and the Islamic Republic share an ideological affinity [PDF] and geopolitical interests that motivate the Houthis to assist Iran, Knights said.

While the Houthis hold Iran’s supreme leader and the Islamic Revolution in high esteem, notable differences separate them from Iran and its closest partners. The Houthis don’t practice the “Twelver” Shiism prevalent in Iran, though they have reportedly incorporated Twelver beliefs into their interpretation of Zaidism. They also weren’t founded with Iran’s help, as groups including Lebanon’s Hezbollah and Iraq’s Badr Organization were. 

How extensive is the military relationship?

Iran is the Houthis’ primary benefactor, providing them mostly with security assistance, such as weapons transfers, training, and intelligence support. In late January 2024, for example, U.S. forces intercepted a shipment carrying military aid from Iran to the Houthis, including drone parts, missile warheads, and anti-tank missile units. Such aid mainly reaches the Houthis via Iran’s paramilitary Islamic Revolutionary Guard Corps (IRGC), which also plays a role advising the Houthis’ military command.

For the Houthis, the Iran connection provides more sophisticated weaponry than they could acquire on their own, especially missiles and drones. Iranian support has bolstered the group’s fighting abilities, helping the Houthis gain and maintain military superiority within Yemen, but experts say it has had greater impact elsewhere. “The role of Iran has been decisive in providing the Houthis with smuggled weapons and expertise to project power into the Red Sea and Bab al-Mandab Strait,” Gulf analyst Eleonora Ardemagni wrote [PDF] for the Yemen-based Sana’a Center for Strategic Studies in 2023.

The Houthis assist Iran by menacing Saudi Arabia’s border and protecting Iranian ships in the Red Sea, giving Iran room to evade sanctions on oil shipping, Iran expert Mohammad Ayatollahi Tabaar writes for Foreign Affairs. At the same time, experts say, the Houthis help field test Iranian-made weapons on Yemen’s front lines and in the Red Sea. Like all axis members, the Houthis offer Iran plausible deniability; members routinely claim responsibility for attacks likely ordered or perpetrated by Iran. For instance, many experts blame Iran for attacks on Saudi Arabia’s oil facilities that the Houthis claimed in September 2019.

How have ties been affected by the Israel-Hamas war?

In what the Houthis have called a show of support for Hamas and Palestinians, the group has attacked U.S.- and Israel-linked targets in the Red Sea and even fired missiles at Israel, with ruinous effects for international shipping. According to data from the International Institute for Strategic Studies, the Houthis have attempted more than three hundred attacks on ships in the Red Sea from November 2023 to December 2024. Experts say it is unclear whether Iran or Houthi leaders ordered the initial strikes, but Tehran has voiced its unequivocal support for the operations and reportedly assists the Houthis in targeting vessels. 

The Houthi threat in the Red Sea concerns Washington especially, as freedom of navigation is a core U.S. interest. In response to the group’s initial shipping attacks in 2023, the United States—under President Joe Biden—worked with the United Kingdom to launch a joint military campaign bombing Houthi targets in Yemen while U.S. and European Union naval missions protected ships in the Red Sea. Israel also conducted its own air strikes on Yemen in 2024—mostly attacking critical infrastructure, such as power stations, oil supplies, and airport and maritime control towers.

In March 2025, the Donald Trump administration launched a new offensive on what it said were Houthi military and strategic targets in Yemen. Houthi sources said the attack killed fifty-three people—including women and children—while U.S. defense officials said top Houthi commanders were among those killed. The reports could not be independently verified. In response, the Houthis claimed retaliatory strikes on U.S. warships in the Red Sea.

The exchange came days after the Houthis announced they would resume attacks on Israeli ships in Mideast waterways after Israel missed a deadline to resume aid deliveries to Gaza. (Houthi attacks were briefly paused after Israel and Hamas reached a cease-fire deal in mid-January.) In a statement on state television, General Hossein Salami, head of Iran’s IRGC, denied any involvement in the Houthis’ retaliatory attacks, saying the IRGC “plays no role in setting national or operational policies” for the militant groups it’s aligned with in the region. Salami also warned that Iran would execute a “decisive and devastating response to any threat” made on Iran, without explicit mention of the United States. Analysts say Washington’s latest campaign, which includes pointed warnings to Tehran to cease support for the Houthis, marks a significant escalation of the conflict in scope and scale.

Clara Fong contributed to this In Brief.

*A correction was made on March 24, 2025: An earlier version of this In Brief stated that the Trump administration launched a new offensive on Yemen in March 2024. The strikes occurred on March 2025.