The U.S. military said Saturday that coalition forces halted an airstrike in progress against the Islamic State in Iraq and Syria (ISIS) after Russian officials said the strike may have hit Syrian forces instead.
The airstrike took place south of Deir Ezzor, Syria, earlier Saturday, U.S. Central Command said in a statement.
"Coalition forces believed they were striking a Da’esh fighting position that they had been tracking for a significant amount of time before the strike," Centcom said, using another name for ISIS. "The coalition airstrike was halted immediately when coalition officials were informed by Russian officials that it was possible the personnel and vehicles targeted were part of the Syrian military."
The United Nations Security Council was set to meet behind closed doors Saturday night to discuss the incident, according to Reuters. Reuters also reported that a spokeswoman for the Ministry of Foreign Affairs of the Russian Federation accused the White House of "defending" ISIS.
A Centcom official said the U.S. did not intend to hit Syrian forces. If confirmed, the report would mark the first time the U.S.-led coalition in Syria has struck the Syrian regime, which it does not have the authority to do.
The strike happened around 11 a.m. Eastern, or 5 p.m. local time, and came "at the beginning of a sustained attack," the official said.
There is no casualty figure yet, but the official said, "There were people on the ground that were killed."
Syrian Observatory for Human Rights, a British-based monitoring group, said at least 80 Syrian soldiers were killed in the strike. The Ministry of Defence of the Russian Federation put the death toll at 60.
Centcom said in its statement that the coalition has struck the same area in the past, and its air operations center had informed Russian forces of the plan.
"Syria is a complex situation with various military forces and militias in close proximity, but coalition forces would not intentionally strike a known Syrian military unit," the statement said.
"The coalition will review this strike and the circumstances surrounding it to see if any lessons can be learned."
The misplaced strike could shatter a tentative cease-fire that called for a halt to violence and potential for joint efforts against ISIS between Russia and the U.S.