(NewsNation) — President Joe Biden expressed his “deepest condolences” to the family of the American killed in a drone strike in northeast Syria, but issued a warning to Iran on Friday.

In addition to the U.S. contractor killed after a drone strike Thursday in northeast Syrica, six Americans are injured. The U.S. has retaliated with air strikes on sites in Syria used by groups affiliated with Iran’s Revolutionary Guard, according to the Pentagon.

How is the U.S. responding?

U.S. officials say the precision strikes ordered in response are meant to defend U.S. personnel and limit the risk of escalation.

“At the direction of President Biden, I authorized U.S. Central Command forces to conduct precision airstrikes tonight in eastern Syria against facilities used by groups affiliated with Iran’s Islamic Revolutionary Guards Corps (IRGC),” Secretary of Defense Lloyd J. Austin III said in a statement released by the U.S. Department of Defense on Friday morning. “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.”

The Syrian Observatory for Human Rights, an opposition war monitor, put the death toll from U.S. strikes at 11 Iranian-backed fighters — including six at an arms depot in the Harabesh neighborhood in the city of Deir el-Zour and five others at military posts near the towns of Mayadeen and Boukamal.

Biden spoke during a state visit to Ottawa, Canada on Friday about the U.S. retaliation.

“The United States does not … seek conflict with Iran,” Biden said. But he said the U.S. is prepared “to act forcefully to protect our people. That’s exactly what happened last night.”

What is the status on the wounded soldiers from the drone attack?

According to the Pentagon, two injured service members were treated on site, and three additional service members and the injured U.S. contractor were transported to coalition medical facilities in Iraq.

Where did the drone come from?

US intelligence officials believe the unmanned aerial vehicle to be of Iranian origin, according to a statement released Friday morning.

Was there another attack in Syria?

U.S. Defense officials have confirmed to ABC News and NBC News that at 8:05 a.m. Friday local time, another base used by the U.S. military in Syria was subject to an attack.

“On the morning of March 24th, at approximately 8:05 am local time, 10 rockets targeted coalition forces at the Green Village in northeast Syria,” Pentagon spokesman Lt. Col. Phil Ventura, to ABC News.

There were no reported casualties from this attack.

The Associated Press contributed to this report.