U.S. Launches Airstrikes After a Drone Attack in Syria Kills American Contractor

WASHINGTON — The United States launched airstrikes in eastern Syria against militant sites linked to Iran’s Islamic Revolutionary Guards Corps after a suspected Iranian drone killed a U.S. contractor and wounded six other Americans, the Pentagon said.

The retaliatory strikes came hours after the self-destructing drone struck a maintenance facility on a coalition base in northeast Syria on Thursday, the Pentagon said in a statement. A U.S. contractor was killed and another contractor and five U.S. service members were injured.

U.S. intelligence analysts concluded that the drone was of “Iranian origin,” and Defense Secretary Lloyd J. Austin III responded by ordering airstrikes against facilities in eastern Syria used by groups affiliated with Iran’s Islamic Revolutionary Guards Corps, or I.R.G.C.

“As President Biden has made clear, we will take all necessary measures to defend our people and will always respond at a time and place of our choosing,” Mr. Austin said. “No group will strike our troops with impunity.”

United States Air Force F-15E fighter jets attacked a munition warehouse, a control building and an intelligence-collection site, two senior U.S. military officials said.

The U.S. airstrikes killed eight pro-Iran fighters, according to the Syrian Observatory for Human Rights, a group in Britain that tracks the conflict through contacts in Syria.

The attacks are likely to stoke tensions with Iran, which Biden administration officials call the largest security threat in the Middle East.

“Iran’s vast and deeply resourced proxy forces spread instability throughout the region and threaten our regional partners,” Gen. Michael E. Kurilla, the head of the military’s Central Command, said in testimony to the House Armed Services Committee earlier on Thursday.

The Islamic Revolutionary Guards Corps is a powerful branch of Iran’s armed forces that operates in parallel with the military. It is charged with securing Iran’s borders, and its overseas arm, the Quds Force, carries out operations across the Middle East and beyond, and trains and arms Shiite proxy militias that operate in a number of countries. The U.S. has designated it a terrorist group.

Iran has built increasingly sophisticated weapons-capable drones in recent years. It has both sold them commercially to other nations, including to Russia for use in the war in Ukraine, and stepped up their transfer to proxy groups.

The drones are part of a rapidly evolving threat from Iranian proxies in Syria, with militia forces specialized in operating more sophisticated weaponry hitting some of the most sensitive American targets in attacks that evaded U.S. defenses.

Two of the wounded service members were treated on site, while the three other service members and the contractor were medically evacuated to coalition medical facilities in Iraq. The Pentagon did not identify the contractor who was killed, pending notification of family, a senior military official said.

America still has more than 900 troops, and hundreds more contractors, in Syria, working with Kurdish fighters to make sure there is no resurgence of the Islamic State, which was ostensibly defeated as a self-declared caliphate in 2019, after five years of wreaking havoc across Iraq and Syria.

Iranian-backed militias have launched dozens of attacks at or near bases where U.S. troops are in the past year alone. U.S. and partner forces with a coalition that includes the Kurdish Syrian Democratic Forces have been working together to keep pressure on Islamic State militants and to ensure that detained fighters do not end up back on the battlefield.

The Kurdish Syrian forces conduct targeted raids against Islamic State members. They also guard more than 10,000 imprisoned Islamic State fighters, while the Pentagon and American troops provide air support, intelligence and reconnaissance.

With the Biden administration focused on Russia’s invasion of Ukraine and a potential future conflict with China, the counter-Islamic State military mission in Syria has become something of a back-burner issue.

The mission has received greater attention only when Iranian-backed militias or Islamic State militants attack the American troops who rotate in and out, for nine months at a time, across a handful of bases in northeast Syria, which Gen. Mark A. Milley, the chairman of the Joint Chiefs of Staff, visited this month.

The United States has repeatedly carried out airstrikes in response. In June 2021, it struck facilities used by two Iranian-backed militias in Iraq and Syria that the Pentagon said had conducted drone strikes against American personnel in Iraq. In December 2019, the U.S. military struck five targets in Iraq and Syria controlled by an Iranian-backed paramilitary group in retaliation for a rocket attack that killed an American contractor.

John Yoon contributed reporting from Seoul.