The Syrian government accused US-led coalition jets of bombing a regime military position on Saturday in the eastern province of Deir el-Zour, labeling the incident a "serious and flagrant aggression."
A statement from the Syrian defense ministry accused the US coalition of targeting its troops in the area near the Deir el-Zour airport around 5 p.m. local time, leading to a "loss of lives and material."
In a statement posted to Facebook, Russia's military said it had been informed some 62 Syrian troops were killed and about 100 others injured.
According to the Associated Press, an Obama administration official expressed US regret for the "unintentional loss of life" after the strikes on Syrian forces.
On Saturday afternoon, U.S. Central Command released a statement maintaining that coalition forces believed they were conducting a strike against ISIS fighters "that they had been tracking for a significant time."
"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 statement read.
Pentagon Press Secretary Peter Cook said in a statement the coalition had informed Russian officials that aircraft would be operating in the area, and that, "no concerns were voiced at the time."
"While we are still trying to determine all the facts, if we mistakenly struck a Syrian military position we regret doing so, especially the loss of lives," Cook said.
The Syrian military also said the airstrike enabled ISIS militants, whom the US coalition was established to target, to advance on a strategic hill.
Using the Arabic acronym for ISIS, the Syrian military said the incident was "firm proof of the US support of Daesh and other terrorist groups." President Bashar al-Assad and his government has labeled all opposition fighters as terrorists.
If confirmed, the incident would mark the first time coalition jets have bombed Syrian government forces.
However, Central Command said coalition fighters would not intentionally target Syrian government forces.
"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, officials said," according to Central Command. "The coalition will review this strike and the circumstances surrounding it to see if any lessons can be learned."
The alleged bombing comes the same week a tentative ceasefire took hold in Syria on Monday as part of a US-Russian negotiated deal.
The incident prompted the United Nations Security Council to schedule an emergency meeting Saturday night to address the strike, the Associated Press reported.
The meeting was scheduled at Moscow's request. On Sunday, Russian foreign ministry spokesperson Maria Zakharova told Russian TV the strikes put the entire peace process in doubt.
“They [US airstrikes] not only call into question… but put in jeopardy everything that has been reached by the international community both within the framework of the International Syria Support Group, the UN Security Council, and on bilateral basis."
Speaking Saturday, Zakharova also said Moscow wanted a "full and detailed explanations about whether this was deliberate support of the Islamic State or another mistake."
She also accused the White House "defending the Islamic State."
However, Washington's ambassador to the UN, Samantha Power, called Russia's convening of the Security Council "a stunt replete with moralism and grandstanding" that was "uniquely cynical and hypocritical."
She criticized Moscow for not calling for the Security Council to meet to investigate the Assad regime's war crimes. "These are some of the most systematic atrocities that we have seen in a generation," Power said. "And not only are [Russia] not interested in seeing these crimes investigated, they’ve used their veto on the Security Council to block meaningful action."
In their statement, the Russian military said that if the airstrike was caused by incorrect coordinates, "it is a direct consequence of the stubborn unwillingness of American side to coordinate their actions with Russia against terrorist groups in Syrian territory."
An unidentified official told CNN's Pentagon correspondent that "condolence payments" to the families of the Syrian troops would be considered "based on claims presented."
"We will review all aspects of this strike to determine what if any lessons should be learned," Cook said.