The United States military launched an air assault on dozens of sites in Iraq and Syria used by Iranian-backed militias on Friday, in the opening salvo of retaliation for the drone strike that killed three US troops in Jordan last weekend, officials said. 

President Joe Biden and other top US leaders have been warning for days the US would strike back at the militias, and they made it clear it wouldn’t be just one hit, but a “tiered response” over time. The officials spoke on condition of anonymity. 

The initial strikes by manned and unmanned aircraft hit command and control headquarters, ammunition storage and other facilities. And they came hours after Biden and top defence leaders joined grieving families to watch as the remains of the three Army Reserve soldiers were returned to the US at Dover Air Force Base in Delaware. 

The bulk carrier Gibraltar Eagle is seen off Kristiansand, Norway. Houthi rebels fired a missile striking the US-owned ship. Photo / AP 

It was unclear what the next steps will be, or whether the days of US warnings have sent militia members scattering into hiding, making it more difficult for the US to detect and strike them. But it was evident the recent statement released by Kataeb Hezbollah, one of the main Iran-backed militias, saying it was suspending attacks on American troops, had no impact on the administration’s plans to strike back. 

The US strikes also appeared to stop short of directly targeting Iran or its Revolutionary Guard Quds force. Iran has denied it was behind the Jordan strike. 

The US has bolstered defences at a base in Jordan that Iran-backed militants attacked as it prepares for a wider US response to the drone attack that killed three service members, a US official said on Friday. 

Attack ‘crossed a line’ 

Even as a larger US military response seemed imminent, some Iran-backed factions pledged to continue to attack US forces in the Middle East. In a statement released on Friday, one of Iraq’s strongest Iran-backed militias, Harakat al-Nujaba, announced its plans to continue military operations against US troops despite other allied factions having called off their attacks in the wake of the Sunday drone strike in Jordan. 

Some of the militias have been a threat to US bases for years, but the groups intensified their attacks in the wake of Israel’s war with Hamas following the October 7 attack on Israel. The war has led to the deaths of thousands of civilians in Gaza and spilled across four other countries now. Iran-backed militia groups throughout the region have used the conflict to justify striking Israeli or US interests, including threatening civilian commercial ships and US warships with drones or missiles in almost daily exchanges. 

On Friday, the Israeli military said its Arrow defence system intercepted a missile that approached the country from the Red Sea, raising suspicion it was launched by Yemen’s Houthi rebels. The rebels did not immediately claim responsibility. 

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A second US official said the military had taken additional self-defence strikes inside Yemen on Friday against Houthi military targets deemed an imminent threat. Al-Masirah, a Houthi-run satellite news channel, said British and American forces conducted three strikes in the northern Yemeni province of Hajjah, a Houthi stronghold. 

While previous US responses in Iraq and Syria have been more limited, the attack on Tower 22, as the Jordan outpost is known, and the deaths of the three service members had crossed a line, the official said. In response, the US is weighing a much-wider response to include striking militia leaders. The US options under consideration include targets in Syria, Yemen and Iraq, where the Iranian-made drone that killed the service members was fired from, the official said. 

Also on Friday, the US Treasury imposed new sanctions on a network of firms in Iran and Hong Kong that are accused of assisting Iran procure technology to make ballistic weapons and drones. And the US hit six Iranian officials with sanctions for allegedly committing a series of malicious cyber activities against critical infrastructure in the US and other nations. 

The attack on Tower 22 led to the first combat deaths of US service members since the war between Israel and Hamas broke out. US response options were being weighed as President Joe Biden, Defence Secretary Lloyd Austin and Joint Chiefs chairman General C.Q. Brown travelled to Dover Air Force Base in Delaware to be with the families of those fallen soldiers as their remains were returned to the US 

The US has blamed the Jordan attack on the Islamic Resistance in Iraq, a coalition of Iranian-backed militias. In the days since the attack, the US has bolstered the defences around Tower 22, which houses about 350 US troops and sits near the demilitarised zone on the border between Jordan and Syria. The Iraqi border is only 10km away. 

The US military base known as Tower 22 in northeastern Jordan. Photo / AP 

Iran ‘training militias’ 

Defence Secretary Austin indicated the US response against the militias would widen. 

“At this point, it’s time to take away even more capability than we’ve taken in the past,” Austin said in his first press conference since he was hospitalised on January 1 due to complications from prostate cancer treatment. 

He said Iran had had a hand in the attacks by supplying and training the militias. The US has tried to communicate through back channels to Iran over the past few months to get it to rein in the militant groups, another US official said. 

The US has also tried more-limited military responses in a series of strikes against weapons storage sites and training areas. So far, the US response has not deterred the groups, which have attacked US facilities at least 166 times since October. 

At least one group, Kataib Hezbollah, another powerful Iranian-backed Iraqi militia that has been watched closely by US officials, said this week it would “suspend military and security operations against the occupying forces” to avoid embarrassing the Iraqi government in the wake of the Jordan attack. 

-Tara Copp, Abdulrahman Zeyad and Lolita C. Baldor, AP