Russia decried Washington's "persistent refusal" to work with the Kremlin after US airstrikes killed dozens of Syrian soldiers, apparently mistaking them for terrorists. The incident could end the peace deal on Syria.
The Russian Foreign Ministry urged the United States to conduct a "most through investigation" and ensure that such incidents are not possible in the future, officials said in a statement on Sunday.
The Saturday night raid, which the US claims was unintentional, lasted for 40 minutes and killed at least 90 regime troops near Deir el-Zour on Saturday, according to the UK-based Syrian Observatory for Human Rights. Damascus and Moscow put the death toll to 62. The Syrian regime said that several tanks and military vehicles were destroyed in the bombing, alongside with four mortars and an anti-aircraft gun.
After the attack, the US military said that the coalition sortie was launched against the "Islamic State" (IS) group that battles the regime forces in the area. They added that the strike was aborted as soon as Moscow raised the alarm in the Pentagon.
However, the IS militia used the airstrike to push the regime troops out of the targeted region, although Damascus has claimed it reclaimed most of the lost ground.
In the Sunday statement, Russia accused the Western pilots of acting "on the boundary between criminal negligence and direct connivance with Islamic State terrorists."
Also on Sunday, IS announced it had shot down a regime plane above Deir el-Zour.
Diplomatic row jeopardizes truce
The strikes prompted the Kremlin to request an emergency UN Security Council meeting on Saturday evening. While the session itself was closed to the press, representatives of both sides used unusually harsh language when discussing the issue with reporters in New York.
Samantha Power, US ambassador to the UN, spoke to the press outside the Security Council chamber while her Russian colleague Vitaly Churkin addressed the diplomats inside.
Power accused Russia of "grandstanding" and pulling a "stunt" by calling for the UN meeting. She also labeled Moscow's actions as "uniquely cynical and hypocritical," claiming that Russia failed to condemn the Syrian President Bashar al-Assad regime for "some of the most systematic atrocities we have seen in a generation."
"Yet in the face of none of these atrocities has Russia expressed outrage, nor has it demanded investigations, nor has it ever called for a Saturday night emergency consultation in the Security Council," she told reporters.
In turn, Russia's ambassador Churkin also walked out before Power was due to address the Council. When asked if the bombing could end the joint peace effort by Moscow and Washington, Churkin said it was "a very big question mark."
"I would be very interested to see how Washington is going to react," he told reporters. "If what Ambassador Power has done today is any indication of their possible reaction then we are in serious trouble."
Syria accuses US of intentionally sinking truce
Syria's UN ambassador Bashar Ja'afari said on Sunday that the US-led coalition air strikes were aimed to intentionally jeopardize the ceasefire deal.
Speaking on the sidelines of the Non-Aligned Movement summit in Venezuela, Ja'afari said: "The aim of the aggression is to make the ceasefire between Russia and the United States fail." He said that there was no way the air strikes could have happened because of a "technical error."
Ja'afari said that the "violation" of Syrian sovereignty would be "very costly."
Iran, which supports Bashar al-Assad's government , also condemned US military action and suggested that the US is colluding with terrorist factions. "Such moves indicate America supports terrorist groups in Syria," he said.
France foreign minister: Syria wants to undermine ceasefire deal
French foreign minister Jean-Marc Ayrault blamed the Assad regime for undermining the ceasefire truce and said the agreement must be salvaged "at all costs."
"We must not forget that it is first of all the (Syrian) regime, and it is always the regime, which has jeopardized the US-Russian ceasefire," Ayrault said on the sidelines of a ceremony in New York commemorating the September 11 attacks. World leaders "must latch on to this agreement and keep it alive at all costs," he said.
The Russian Foreign Ministry also slammed US representatives for "not only being unable to provide an adequate explanation of the events but also trying to flip the issue upside down, as usual."
The also lamented Washington's "persistent refusal" to coordinate with Russia when it comes to fighting terror groups in Syria.
Previously, the US Defense Department spokesman Peter Cook said the Pentagon had informed Moscow of its plans to operate in the area and that "no concerns were voiced."
The US relayed its "regret" to Syria through the Russian government, lamenting the unintentional loss of life, a senior White House official told the Reuters news agency. Australia, whose aircraft took part in the strike, also offered "condolences to the families of any Syrian personnel killed or wounded."
Australia would "never intentionally target a known Syrian military unit or actively support Daesh [IS]" the military said in a statement.
Syria's army labeled the strikes as "conclusive evidence" of US support for IS, calling them "dangerous and blatant aggression."