Seventeen people have been reported killed after the United States military carried out attacks on facilities in eastern Syria used by Iran-backed militia on Thursday, following recent rocket attacks on US troop locations in Iraq. It was the first military airstrikes to be conducted by the fledgling Joe Biden administration which took office last month.

“At President Biden’s direction, US military forces earlier this evening conducted airstrikes against infrastructure utilized by Iranian-backed militant groups in eastern Syria,” Pentagon spokesman John Kirby in a statement.

“These strikes were authorised in response to recent attacks against American and Coalition personnel in Iraq, and to ongoing threats to those personnel,” he said.

According to the Pentagon, US fighter jets dropped seven 500-lb Joint Direct Attack Munition-guided precision bombs, hitting seven targets, which includes a crossing used by the armed groups to move weapons across the border.

Kirby said the strikes destroyed multiple facilities at a border control point used by a number of Iranian-backed militant groups, including Kata’ib Hezbollah (KH) and Kata’ib Sayyid al-Shuhada (KSS).

The Syrian Observatory for Human Rights said more than a dozen pro-Iran fighters were killed.

“The strikes destroyed three lorries carrying munitions… There were many casualties. Preliminary indications are that at least 17 fighters were killed, all members of Popular Mobilisation Forces,” SOHR director Rami Abdul Rahman, told AFP news agency.

The group said all the dead were from the Hashed al-Shaabi, an umbrella organisation that includes KH and KSS.

The United States move came after an attack nearly two weeks ago on the main military base inside the airport in Erbil, which killed one foreign civilian contractor and wounded at least nine others, including an American soldier. Foreign troops deployed as part of the US-led coalition that has helped Iraq fight the armed group ISIL (also known as ISIS) since 2014, are stationed at the site.

A shadowy group calling itself Awliya al-Dam – or the Guardians of the Blood – claimed responsibility for the attack and said it would continue to attack “occupation” American forces in Iraq.

The Pentagon statement described the US military response as “proportionate”, co-ordinated with diplomatic measures and carried out in consultation with coalition partners.

“We have acted in a deliberate manner that aims to de-escalate the overall situation in both eastern Syria and Iraq,” it said.

•Additional reports by AFP and Al Jazeera.

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