OTTAWA, Ontario -- President Joe Biden said Friday that the U.S. would respond "forcefully" to protect its personnel after U.S. forces retaliated with airstrikes on sites in Syria used by groups affiliated with Iran's Revolutionary Guard after a suspected Iranian-linked attack Thursday that killed a U.S. contractor and wounded seven other Americans in northeast Syria.
"The United States does not, does not, seek conflict with Iran," Biden said in Ottawa, Canada, where he is on a state visit. But he said Iran and its proxies should be prepared for the U.S. "to act forcefully to protect our people. That's exactly what happened last night." Activists said the U.S. bombing killed at least four people.
While it's not the first time the U.S. and Iran have traded strikes in Syria, the attacks and the U.S. response threaten to upend recent efforts to deescalate tensions across the wider Middle East, whose rival powers have made steps toward detente in recent days after years of turmoil.
The Pentagon said a drone attack on a U.S. base Thursday killed a contractor and injured five U.S. troops and another contractor. That was followed by two simultaneous attacks on U.S. forces in Syria on Friday, according to U.S. officials.
The officials said that based on preliminary information, there was a rocket attack Friday at a Conoco plant, and one U.S. service member was injured but is in stable condition. At about the same time, several drones were launched at Green Village, where U.S. troops are also based. One official said all but one of the drones were shot down, and there were no U.S. injuries there. The officials spoke on condition of anonymity to discuss military operations.
Two Syrian opposition activist groups reported a new wave of airstrikes on eastern Syria that hit positions of Iran-backed militias after rockets were fired at a Conoco gas plant that has a base housing American troops. Several U.S. officials, however, said the U.S. did not launch any attacks late Friday, and it wasn't clear if the activists were referring to the attack on U.S. forces at Green Village.
U.S. Defense Secretary Lloyd Austin said the American intelligence community had determined that the drone in Thursday's attack was of Iranian origin. U.S. officials said that conclusion was based on recovered debris and intelligence threat streams. They offered no immediate evidence to support the claim. The drone hit a maintenance facility at a coalition base in the northeast Syrian city of Hasaka.
In retaliation, the Pentagon said F-15 fighter jets flying out of al-Udeid Air Base in Qatar struck several locations around Deir el-Zour. Those strikes, Austin said, were a response to the drone attack "as well as a series of recent attacks against coalition forces in Syria" by groups affiliated with the Revolutionary Guard.
Iran relies on a network of proxy forces through the Mideast to counter the U.S. and Israel, its archenemy in the region. The U.S. has had forces in northeast Syria since 2015, when they deployed as part of the fight against the Islamic State group, and maintains some 900 troops there working with Kurdish-led forces that control around a third of Syria.
Overnight, videos on social media purported to show explosions in Deir el-Zour, a strategic province that borders Iraq and contains oilfields. Iranian-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.
Reports on the number of killed and wounded in the U.S. strikes varied. Activist group Deir Ezzor 24, which covers news in the province, said four people were killed and a number of others were wounded. The Syrian Observatory for Human Rights, an opposition war monitor, said 11 Iranian-backed fighters were killed -- including six at an arms depot in the Harabesh neighborhood in Deir el-Zour and five at military posts near the towns of Mayadeen and Boukamal.
Rami Abdurrahman, who heads the Observatory, said three rockets were fired earlier Friday at the al-Omar oilfield in Deir el-Zour that houses U.S. troops, an apparent retaliation to the American strikes.
The Associated Press could not immediately independently confirm the activist reports. Iran and Syria did not immediately acknowledge the strikes, and their officials at the United Nations in New York did not respond to requests for comment from the AP.
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.
The exchange of strikes came as Saudi Arabia and Iran have been working toward reopening embassies in each other's countries. The kingdom also acknowledged efforts to reopen a Saudi embassy in Syria, whose President Bashar Assad has been backed by Iran in his country's long war.
U.S. Army Gen. Erik Kurilla, the top U.S. commander for the Middle East, warned that its forces could carry out additional strikes if needed. "We are postured for scalable options in the face of any additional Iranian attacks," Kurilla said in a statement.
On Thursday, Kurilla warned Congress during a hearing that the "Iran of today is exponentially more militarily capable than it was even five years ago." He pointed to Iran's arsenal of ballistic missiles and bomb-carrying drones.
Information for this article was contributed by Abby Sewell, Qassim Abdul-Zahra, Zeke Miller and Lolita C. Baldor of The Associated Press.