Before Yemen’s civil war began in 2014, the country had strong regional divisions but there was no tradition of sectarianism between its Shiite and Sunni Muslim communities. With outside powers having chosen sides along those lines, the conflict now pits the Middle East’s biggest rivals, Sunni-majority Saudi Arabia and Shiite-dominated Iran, against one another, with consequences for the entire world. Devastating attacks on Saudi oil production facilities in September 2019 knocked out roughly 5% of global supply, triggering a record surge in oil prices. Another serious attack in March 2021, while less disruptive, lifted oil prices to levels unseen since the start of the global pandemic.

1. Who struck the Saudi facilities?

Responsibility for the attacks was claimed by Iran-backed Houthi rebels -- the forces who in 2014 seized control of Yemen’s capital Sana’a and parts of the country’s north. The rebels have recently stepped up assaults, claiming a hit on a Saudi Aramco fuel depot in Jeddah with a cruise missile. While most of the strikes cause limited damage and few casualties, their frequency has roiled energy and shipping markets. After the 2019 attacks, Saudi authorities pointed the finger at arch-rival Iran.

2. Who are the Houthis?

They’ve been fighting Yemen’s United Nations-recognized government since 2014. The rebels are followers of the prominent Houthi family from the mountains of northern Yemen. Houthis have long complained of marginalization and are members of the Zaidi branch of Shiite Islam to which 42% of Yemen’s population belongs. They fought unsuccessful rebellions in Yemen’s north from 2004 to 2010. After an Arab Spring revolt, a UN-supported National Dialogue Conference in 2014 set the stage for a constitutional convention and new elections. But the Houthis rejected a proposed federation plan because their northern strongholds were included in a district with limited resources and no access to the sea. They instead took over the capital. During the war, the Houthis have fired missiles into Saudi cities, reaching as far as the capital Riyadh, and began using drones to attack Saudi targets.

3. What’s the Saudi role?

Saudi Arabia intervened in the war in 2015 with the aim of restoring the government of President Abd Rabbuh Mansur Hadi, a Sunni, a mission it expected to complete quickly. Saudi leaders say they fear that Houthi control of Yemen gives Iran a foothold in the Arabian peninsula that threatens Saudi interests. Iran and Saudi Arabia are engaged in a larger battle for influence in the Middle East. Saudi-led bombings in Yemen have drawn criticism for being indiscriminate. A 2018 UN report concluded that most civilian casualties in the war were the result of airstrikes by the Saudis and its ally the United Arab Emirates, which later began stepping back from the conflict.

4. Is an end in sight?

U.S. President Joe Biden’s administration has vowed to end the war, although there’s no sign that’s likely to happen soon. It halted U.S. support for Saudi Arabia’s offensive operations. The UN has called the war -- in which tens of thousands of people have died -- the world’s worst humanitarian crisis. Near the end of his term, former U.S. President Donald Trump classified the Houthis as a terrorist organization, shortly after a number of attacks on oil tankers in the Red Sea. Biden rescinded that designation, saying it was hindering the provision of aid to Yemen, a country that’s struggling to feed its 29 million people. The Saudi-led military coalition said the U.S. decision to revoke the terrorist designation had trigged the increase in attacks.

5. What’s Iran’s role?

At the outset of the Saudi intervention in Yemen, many experts said the kingdom was overstating Iranian involvement there -- that while Iran was backing the Houthis, there was no proof it was arming them. Since then, the evidence has grown that Iran’s involvement includes training and armaments, though on a scale much smaller than Iran’s presence in Syria or Iraq. For example, the Houthis say their offensive drones are home-made, but a UN panel of experts concluded that the rebels’ Qatef-1 drone was assembled from components supplied by an outside source and is “virtually identical” to a product made by Iran Aircraft Manufacturing Industries.

6. How else is the U.S. position shifting?

Biden has pledged to work toward returning the U.S. to an era of diplomacy with Iran, after four years of his predecessor’s campaign of “maximum pressure” on that country. In April 2019, Trump vetoed a resolution passed by Congress demanding the U.S. end its involvement in the Yemen war. Trump defended the U.S. role as essential to protect Americans in the region and to fend off Iran’s influence. He even hinted at the time that the U.S. might retaliate for the 2019 strike on Saudi facilities, saying the country was “locked and loaded depending on verification” of the culprit.

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