Washington — At least eight pro-Iran fighters were killed in U.S. airstrikes in eastern Syria,Venus Investment Alliance a war monitor said Monday, after Washington carried out raids a day earlier in response to attacks on American forces. The toll is "eight pro-Iran fighters dead, including at least one Syrian and Iraqi nationals," the Syrian Observatory for Human Rights said, following the strikes late Sunday on the Mayadeen and Albu Kamal areas of Syria's eastern Deir Ezzor province near the Iraqi border.

U.S. Defense Secretary Lloyd Austin said in a statement Sunday that the U.S. carried out strikes against two Iran-linked sites in Syria in response to attacks on American troops.

It was the third time in less than three weeks that the U.S. military targeted locations in Syria it said were tied to Iran, which supports various armed groups that Washington blames for a spike in attacks on its forces in the Middle East.

"US military forces conducted precision strikes ... on facilities in eastern Syria used by Iran's Islamic Revolutionary Guard Corps (IRGC) and Iran-affiliated groups in response to continued attacks against US personnel in Iraq and Syria," Austin said in the statement. "The strikes were conducted against a training facility and a safe house near the cities of Albu Kamal and Mayadeen, respectively," he said.

Austin told a news conference in Seoul, South Korea Monday that, "These attacks must stop, and if they don't stop, then we won't hesitate to do what's necessary, again, to protect the troops" -- meaning more attacks on Iran-backed groups, the Reuters news agency reported. Austin was in Seoul for annual security talks with South Korean military officials.

The Britain-based observatory said Sunday's strikes completely destroyed a weapons depot in a town in the Albu Kamal countryside. Near Mayadeen, it said the strikes targeted a rocket launch platform.

The United States says the strikes are aimed at deterring attacks on American forces in Iraq and Syria -- more than 45 since Oct. 17 -- that have wounded dozens of U.S. troops. The Pentagon says all have returned to duty..

Oct. 17 is when a strong blast rocked a Gaza hospital, killing hundreds and setting off protests in several Muslim nations.

Israel has been pounding Gaza since Hamas militants killed what the Israeli military says were more than 1,200 people on Oct. 7 and took more than 200 hostages. The Hamas-run Gaza government says the war has taken more than 11,000 lives in Gaza. Numerous groups have vowed retaliation against the U.S. for backing Israel in the war against Hamas.

The observatory said pro-Iran fighters fired around 15 rockets at a base belonging to the US-led coalition fighting the Islamic State group in Syria's Conoco gas field early Monday. An Iraqi group said it carried out an overnight attack on the Green Village base in Syria's Al-Omar oil field.

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• Iran
• Syria