In July, Saudi Arabia and the United States bombed Iran-backed militias in Iraq after blaming them for drone attacks on Saudi oil facilities that had been claimed by Yemen's Houthi rebels, another Iranian ally.
Now, regional officials tell The Associated Press that the Houthis helped the Iraqi militias plan and execute the two-day swarm attack, showing a new level of coordination.
Iran spent decades building up armed groups on Israel's frontiers that suffered major losses in the wars following Hamas' Oct. 7, 2023, attack out of Gaza. Israel battered the Palestinian militants as well as Lebanon's Hezbollah, which had been Iran's most powerful ally.
Regional officials and experts say Iran is now using the Iraqi militias and the Houthis to threaten Saudi Arabia and other American allies in the Gulf in order to drive up the costs of the war launched by the U.S. and Israel in February.
It is a risky strategy. A wave of Houthi attacks on Saudi oil facilities on Tuesday threatened to reignite full-scale war with the kingdom. Iraq has ordered militias to disarm by the end of this month, though powerful Iran-backed groups have refused to do so. A new American effort to economically isolate Iran could spark further escalation.
Iran-backed groups in Yemen and Iraq form a pincer movement
The Houthi involvement in the Iraqi drone attack was confirmed by two Saudi officials, citing intelligence, and a senior Iraqi security official. They said Houthi emissaries worked in an operations room run by Iraqi militias.
Saudi Arabia and the U.S. responded with joint airstrikes that killed at least 20 Iraqi fighters, six Iranian advisers and at least one Houthi official. The death of the Houthi, not previously reported, was confirmed by a Houthi official and an Iraqi militia member.
A U.S. military official said Houthis had been killed in previous strikes in Iraq. The U.S. is concerned about the Houthi presence there and their ability to launch attacks on other countries, including Saudi Arabia, the official said.
Two officials with the Popular Mobilization Forces, an umbrella group of militias that is officially part of Iraq's security forces, denied involvement in the attack on Saudi Arabia and denied that the Houthis were operating under its auspices. The PMF includes powerful militias backed by Iran that sometimes act independently.
All the officials and the militia member spoke on condition of anonymity because they were not authorized to speak to media. The Houthis did not respond to a request for comment.
Cooperation between the Iraqi militias and the better organized Houthis had grown throughout the war in Gaza, when they coordinated attacks on Israel, according to the Houthi and regional officials. At the height of the war, Houthi leader Abdel-Malek al-Houthi spoke of a joint operations room.
After the U.S. and Israel attacked Iran on Feb. 28, Iran and its allies began firing on Gulf nations to broaden the conflict and inflict pain on major oil producers hosting American forces.
"Iran has a hybrid strategy in the current war. We are not fighting on one front and we are not using one tool," Mahdi Mohammadi, an adviser to Iran's parliament speaker, wrote on social media in June.
"The Houthis' growing prominence during the Gaza war opened up a new horizon in Iraq. Many groups there became eager to support the Houthis, and in return, the Houthis started sharing their military expertise with Iraqi militias," said Ahmed Nagi, senior Yemen analyst at the Crisis Group, an international think tank.
Now they are "squeezing Saudi like with pliers," Nagi said.
Houthi blockade of Saudi Arabia ramps up pressure
A week before the drone swarm attack, the Houthis declared a blockade against Saudi shipping in the Red Sea, threatening another critical trade route as the wartime disruption of the Strait of Hormuz has jolted the world economy.
Since late July, the Houthis have carried out over a dozen attacks against Saudi oil facilities and tankers in the Red Sea, according to the war monitor group ACLED.
On Tuesday, they launched a wave of attacks on oil and other facilities in southern Saudi Arabia, wounding more than 70 people, including women and children, Saudi authorities said.
The Houthi blockade has forced Saudi Arabia to adopt a "dark" transit policy that includes turning off tracking signals on oil tankers in the Red Sea, according to ACLED.
Saudi Arabia had diverted much of its oil to the Red Sea after Iran effectively closed the Strait of Hormuz. When the Houthis began attacking, the kingdom started shipping more oil north to the Suez Canal and Egypt's SUMED pipeline, whose flows have risen from 650,000 barrels a day in June to over 1.9 million in August, according to global shipping monitor Kpler.
Last month, the Houthis showed they can target that route as well, striking a Saudi tanker in the northern Red Sea with a missile. The tanker had reportedly traveled from the Saudi port of Yanbu to the Suez Canal, some 1,000 kilometers (700 miles) from Houthi territory.
The Houthis "are willing to weather some shorter term pain for what they feel will be longer term gains," such as extending their reach along the Red Sea coast, said Adam Baron, a Yemen expert at the New America think tank in Washington.
"The train to a return to full scale war has left the station, and it's unclear if anyone is going to jump in to stop it," he said, citing the U.S. focus on Iran and the Saudis' reluctance to intervene in Yemen again.
The Houthis have their own reasons for fighting Saudi Arabia
The rebels seized Yemen's capital, Sanaa, in 2014. The following year, the Saudis joined with Yemen's internationally recognized government in a counteroffensive, likely fearing that the kingdom could end up with a Hezbollah-like group on its doorstep.
