US troops patrol near an oil field in al-Qahtaniyah in Syria's northeastern Hasakah province on June 14, 2023. (PHOTO / AFP)

WASHINGTON -- US forces conducted precision strikes Thursday against two facilities used by Iran in eastern Syria, Secretary of Defense Lloyd Austin said in a statement.

Austin said the strikes targeted two facilities used by Iran's Islamic Revolutionary Guard Corps and affiliated groups and were carried out at President Joe Biden's direction.

The strikes were "self-defense" in nature, Austin said, and were meant to retaliate "a series of ongoing and mostly unsuccessful attacks against US personnel in Iraq and Syria by Iranian-backed militia groups that began on October 17."

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Due to attacks against US forces, "one US citizen contractor died from a cardiac incident while sheltering in place; 21 US personnel suffered from minor injuries, but all have since returned to duty," he said. 

According to the Syrian Observatory for Human Rights, powerful explosions rocked the Koniko natural gas field, which houses a key US military base, in Syria's eastern province of Deir al-Zour on Thursday night

Multiple attacks targeted US military bases in Syria's eastern region on Thursday, according to the pro-government Sham FM and an oppositional war monitor.

According to the Syrian Observatory for Human Rights, powerful explosions rocked the Koniko natural gas field, which houses a key US military base, in Syria's eastern province of Deir al-Zour on Thursday night.

The explosions caused by strikes originated from areas under the control of the Syrian army and pro-Iran militias in the Deir al-Zour countryside, directly opposing the military base, said the Observatory.

In a simultaneous development, the US forces were observed deploying in the Thiban area in the countryside of Deir al-Zour.

Earlier in the day, a US base in the Shaddadi area in the countryside of the northeastern province of Hasakah was hit by at least two explosions.

Responding to the attacks, the US forces sounded alarms, deployed soldiers, and initiated surveillance of the area with a US drone to monitor the evolving situation.

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The Observatory said that Iranian-backed fighters are believed to be behind the attacks on US military bases in Syria, which intensified since the Israeli military campaign on Gaza started on Oct 7.

The pro-government Sham FM radio also reported the attacks on the US military bases in Shaddadi and Koniko, reporting a state of tension among the US forces, coinciding with the helicopter's flight in the region's sky.

Pro-Iran fighters have allegedly attacked US bases in Iraq as well. The Pentagon said Thursday that there was an attempted attack at Erbil airbase in Iraq. 

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Separately, Syrian President Bashar al-Assad on Thursday slammed long-standing American and European policies for fostering military escalation and chaos across the globe, according to the state news agency SANA.

In a meeting at the Syrian Foreign Ministry, Assad said the core of the American policy has been the "relentless pursuit of military escalation and the deliberate creation of disorder," a strategy that Europe has mirrored.

Also on the day, Syrian Foreign Minister Faisal Mekdad deemed the US and Western's support for Israel in its current campaign in the Gaza Strip as a "blatant endorsement for Israeli forces to carry out atrocities against the Palestinian people."