A war monitor says the death toll has risen from the retaliatory strikes the U.S. launched after a suspected Iranian-backed attack in Syria.
The Britain-based Syrian Observatory for Human Rights said Saturday the U.S. attack left 19 people dead, up from the 14 the Observatory initially reported had died.
U.S. President Joe Biden said the United States would respond "forcefully" to protect Americans after the U.S. military said it carried out airstrikes in eastern Syria in response to a suspected Iranian-backed attack.
Speaking during a state visit to Canada on Friday, Biden said the United States "does not seek conflict with Iran but is prepared to act forcefully to protect our people."
"That's exactly what happened last night," he added.
The U.S. military said it carried out multiple "precision" airstrikes overnight Thursday against targets in eastern Syria in response to a drone attack that killed a U.S. contractor.
Defense Department spokesperson Brig. Gen. Patrick Ryder told reporters at the Pentagon on Friday that the operation was intended "to send a very clear message that we will take the protection of our personnel seriously, and that we will respond quickly and decisively if they are threatened."
He described the strikes as "proportionate and deliberate action intended to limit the risk of escalation to minimize casualties."
The Syrian Observatory for Human Rights, a British-based group that monitors the war in Syria, said 14 people were killed by the U.S. strikes in Syria.
On Friday, U.S. officials said multiple drones were launched at the Green Village in northeast Syria, where U.S. troops are also based. Officials said there were no injuries in those attacks.
In a statement, U.S. Defense Secretary Lloyd Austin described the strikes as mounted against facilities used by groups affiliated with Iran's Islamic Revolutionary Guards Corps.
"The airstrikes were conducted in response to today's attack as well as a series of recent attacks against Coalition forces in Syria by groups affiliated with the IRGC," Austin said.
"No group will strike our troops with impunity," he added.
The drone struck a maintenance facility on a base in Hasaka, Syria, at 1:38 p.m. local time, according to the Pentagon.
Six other Americans were wounded in the attack, including five U.S. service members. Two of the wounded service members were treated onsite, while three others and the U.S. contractor were medically evacuated to coalition medical facilities in Iraq, according to the U.S. military statement.
The United States has about 900 troops in eastern Syria to help Syrian Kurdish forces prevent a resurgence of the Islamic State terror group.
Joint Chiefs of Staff Chairman Gen. Mark Milley, the top U.S. military officer, and the head of U.S. Central Command, which oversees U.S. military operations in the Middle East, warned lawmakers in separate hearings Thursday that Iran continues to destabilize the Middle East through its support to terrorist groups and proxy forces.
Iranian proxies have attacked U.S. troops in Iraq and Syria 78 times using drones and rockets since January 2021, according to CENTCOM commander Gen. Erik Kurilla.
"This was another in a series of attacks on our troops and partner forces," Kurilla said late Thursday.
"We will always take all necessary measures to defend our people and will always respond at a time and place of our choosing. We are postured for scalable options in the face of any additional Iranian attacks," he added.
Some information in this report came from The Associated Press, Reuters, and Agence France-Presse.
