A team of Army Delta Force commandos carried out a raid in
The officials, who were not authorized to speak publicly about the classified operation, said a special operations team carried out the raid Sunday to kill or capture suspected Islamic State leaders in the city of Dair Alzour, about 80 miles southeast of the extremist group's de facto Syrian headquarters in Raqqah.
There were no prisoners taken, the officials said. They did not identify who was killed, or say which Islamic State leaders were targeted in the raid.
Pentagon spokesman Capt. Jeff Davis told reporters that an unspecified expeditionary task force carried out the mission, which he called "routine" and "successful."
"It was focused on ISIL leadership," Davis said, using an acronym for Islamic State. "The U.S., and entire counter-ISIL coalition, will continue to pursue ISIL leaders wherever they are to ensure the security and stability of the region and our homeland."
Activist groups, including the Syrian Observatory for Human Rights, said the operation had taken place on Sunday after 2:30 p.m., when six Apache helicopters flew deep into the desert areas of eastern Syria near the village of Kubar, about 35 miles northwest of Dair Alzour.
The Syrian Observatory for Human Rights is a British-based watchdog group that supports the rebels seeking to overthrow Syrian President
Firsthand accounts recorded on the WhatsApp messaging service and provided to The Times by a local activist, Abdul Rahman Hasson, said two of the helicopters had remained in the air, while troops in the remaining aircraft attacked a number of Islamic State vehicles. Observers reported that the operatives had set up roadblocks to prevent civilians from passing into the area.
"They went down, killed some Daesh fighters and took some others. We have no confirmation of the numbers of those killed," said Ahmad Ramadan, head of the activist-run Euphrates Post group, which is based in Istanbul, Turkey. It purports to have contacts with undercover correspondents in Dair Alzour.
Daesh is the Arabic acronym for Islamic State, which holds sway over much of Dair Alzour province. The group's jihadis have mounted a grueling siege on the provincial capital of the same name, which remains in government hands.
"A van and a pickup with Daesh fighters as reinforcements were destroyed by the helicopters in the air," Ramadan said, adding that the commandos had at least one person who could speak Arabic with them.
Other reports said they had attacked a nearby Islamic State building. The Syrian Observatory for Human Rights said at least 25 Islamic State fighters were killed and others were taken captive, but that account was at odds with what U.S. officials said.
Kubar, a village on the Euphrates River roughly equidistant from Dair Alzour and Raqqah, is thought to be a stronghold for Islamic State and one of Raqqah's first defensive lines.
Hasson said it had a secret Islamic State prison. In the years before the Syrian civil war, it was home to a suspected nuclear reactor that was bombed by a squadron of Israeli F-16 and F-15 warplanes in 2007.
Sunday's operation was the U.S.-led coalition's second direct-action ground raid targeting prominent Islamic State figures in the area. In March 2015, U.S. special forces killed Abu Sayyaf, a leader who was thought to be the group's "oil minister."
Since they were announced in December 2015 by Defense Secretary Ashton Carter, expeditionary task force operations have killed or captured several top militants, and netted key sources of intelligence, including laptops and cellphones. Interrogations of captured militants have shed light on the shadowy group, U.S. officials said.
The Pentagon did not detail what intelligence was gleaned from Sunday's operation.
Special correspondent Bulos reported from Amman, Jordan, and Times staff writer Hennigan from Washington. Staff writer Molly Hennessy-Fiske in Cairo contributed to this report.