A strike Thursday by a suspected Iranian-made drone killed a U.S. contractor and wounded five American troops and another contractor in northeast Syria, the Pentagon said.
American forces said they retaliated soon after with "precision airstrikes" in Syria targeting facilities used by groups affiliated with Iran's Revolutionary Guard, with activist groups saying they killed at least four people.
U.S. forces entered Syria in 2015, backing allied forces in their fight against the Islamic State group. The U.S. still maintains the base near Hasakah in northeast Syria where Thursday's drone strike happened. There are roughly 900 U.S. troops, and even more contractors, in Syria, including in the north and farther south and east.
U.S. Defence Secretary Lloyd Austin said he authorized the retaliatory strikes at the direction of President Joe Biden.
"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," Austin said. "No group will strike our troops with impunity."
Reports of strikes in at least 2 Syrian sites
Austin said in a statement that the American intelligence community had determined the drone was of Iranian origin, but offered no other immediate evidence to support the claim. Iran's paramilitary Revolutionary Guard, which answers only to Supreme Leader Ayatollah Ali Khamenei, has been suspected of carrying out attacks with bomb-carrying drones across the wider Middle East.
Since the U.S. drone strike that killed Revolutionary Guard Gen. Qassem Soleimani in 2020, Iran has sought "to make life difficult for U.S. forces stationed east of the Euphrates," said Hamidreza Azizi, an expert with the German Institute for International and Security Affairs.
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The Pentagon said three of the injured needed to be transported to medical facilities in Iraq.
Overnight, videos on social media purported to show explosions in Syria's Deir el-Zour, a strategic province that borders Iraq and contains oil fields. Iran-backed militia groups and Syrian forces control the area, which also has seen suspected airstrikes by Israel in recent months allegedly targeting Iranian supply routes.
The Syrian Observatory for Human Rights, an opposition war monitor, reported that the American strikes killed six Iranian-backed fighters at an arms depot in the Harabesh neighbourhood in Deir el-Zour. The Observatory, which relies on a network of local contacts in Syria, said U.S. bombing at a post near the town of Mayadeen killed two fighters.
A separate American strike hit a military post near the town of Boukamal along the border with Iraq, killing another three fighters, the Observatory said.
The AP could not immediately independently confirm the activist reports.
Iran and Syria did not immediately acknowledge the strikes, nor did their officials at the United Nations in New York respond to requests for comment from The Associated Press.
The incident again brings to the fore the increased use of drones in warfare. In recent months, Russia has begun using drones in its attacks on sites across Ukraine that Western nations and experts say can be tied to Tehran.
Iran has issued a series of conflicting denials about its drones being used in that war.
Incident could ratchet U.S.-Iran tensions
In the Mideast, Iran relies on proxy forces to counter the activities of the U.S. and Israel.
Israel has carried out hundreds of strikes on targets inside government-controlled parts of Syria in recent years, including an attack on the Aleppo airport this week, but rarely acknowledges or discusses the operations.
Addressing the U.S. House's armed services committee on Thursday, U.S. Army Gen. Michael Kurilla, the head of the American military's Central Command, warned lawmakers that the "Iran of today is exponentially more militarily capable than it was even five years ago."
Kurilla also alleged that Iran had launched some 78 attacks on U.S. positions in Syria since January 2021.
The U.S. also has concerns about the progress of Tehran's nuclear program, after a pact with Iran placing limits on its development was cancelled by Donald Trump.
The attack and the U.S. response threaten to upend recent efforts to de-escalate tensions across the wider Middle East, whose rival powers have made steps toward detente in recent days after years of turmoil.
Saudi Arabia and Iran recently committed to reopening embassies in each other's countries. The kingdom also acknowledged efforts to reopen a Saudi embassy in Syria, whose embattled President Bashar al-Assad has been backed by Iran in his country's long war.
The United Nations estimates over 300,000 civilians have been killed in the Syrian war since 2011. Those figures do not include soldiers and insurgents killed in the conflict; their numbers are believed to be in the tens of thousands.
