Tensions between Russian and U.S. diplomats have spilled over at the United Nations Security Council after Russian officials demanded to know whether the United States intentionally supported Islamic State (IS) militants with air strikes that hit Syrian government troops.
Russia's ambassador to the United Nations, Vitaly Churkin, walked out of the emergency meeting on September 17 -- protesting U.S. Ambassador Samantha Power's description of Russia’s call for the meeting as "a stunt."
Meanwhile, Power accused Russia of a "cynical and hypocritical' attempt at "cheap point scoring" and "grandstanding" by calling for the emergency session.
She said Moscow should, instead, demand a meeting with Syrian President Bashar al-Assad's regime in order to push for peace.
Power said Washington was investigating claims by Russia and Damascus that U.S. air strikes killed scores of Syrian government troops in the east of the country.
She said "if we determine that we did, indeed, strike Syrian military personnel, that was not our intention. And we of course regret the loss of life."
Russia said U.S. air strikes on September 17 killed at least 62 Syrian government soldiers and helped Islamic State militants seize a strategic hilltop overlooking a government-controlled air base near Deir al-Zor.
Churkin said the air strikes left "a very big question mark" over the future of a September 12 cease-fire deal brokered by Russia and the United States that is aimed at restarting Syria's peace process.
The deal includes a fragile nationwide truce, improved humanitarian aid access, and joint military targeting of banned Islamic militant groups by Russia and the United States.
Churkin said U.S. forces could have held off on air strikes near Deir al-Zor for two more days, when Moscow and Washington are meant to start joint military cooperation, instead of carrying out what he called a "reckless" operation.
But a Pentagon spokesman said that Russia had not expressed any concerns when initially informed that coalition forces would be operating in the area.
Earlier, Russian Foreign Ministry spokeswoman Maria Zakharova was quoted by Russia's state-run TASS news agency as saying the Kremlin had "come to the terrible conclusion that the White House is defending the Islamic State."
A statement from the U.S. Central Command on September 17 said "coalition forces would not intentionally strike" Syrian government forces.
It said coalition air strikes were "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 London-based Syrian Observatory For Human Rights said it was unable to confirm who carried out the air strikes.
It said Russian jets had been carrying out bombing raids at the same time in the area in support of Syrian forces engaged in battle against IS militants at Jebel Tharda, which is near Deir al-Zor.
Sergei Rudskoy, head of the operations directorate of the Russian Armed Forces' General Staff, denied the reports from the London-based monitoring group -- telling journalists in Moscow early on September 18 that Russian aircraft "were definitely not used in this region at this time."
Rudskoy said Russia thinks the incident "became possible because the United States does not know the situation and does not want to coordinate with Russia on fighting against terrorist groups in Syrian territory."
Syria called the air strikes a "serious and blatant attack on Syria and its military," and "firm proof" of U.S. support for IS militants "and other terrorist groups."
Russia and the United States have criticized each other for not following through on agreements that are part of the September 12 cease-fire deal.