Washington has broken its promise to separate the powerful Jabhat Fateh al-Sham — the successor organization to the Nusra Front after it renamed itself on July 28 — and other extremist groups from U.S.-backed moderate rebels, Russian Foreign Minister Sergei Lavrov said Friday.

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"They still are not able or willing to do this ... We believe the plan was to spare Nusra," said Lavrov. "They have never touched Nusra anywhere in Syria."

The statements came a day after the Kremlin announced that the Russian Aerospace Forces would continue its “war on terror” in support of Syrian government forces.

According to the BBC, Lavrov defended the Russian bombardment of the besieged city of Aleppo by Russian and Syrian government forces. The United Nations released a report saying that 400 civilians, including many children, were killed in the city within the past week.

Russia has been conducting airstrikes against the Islamic State group and other extremists groups since last September at the Syrian government’s request.

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Meanwhile ,Washington and its regional allies have been carrying out airstrikes against what they call Islamic State group positions in Syria and neighboring Iraq since 2014. However, last week they killed Syrian 62 soldiers.

The war in Syria, which started in early 2011, has killed more than 400,000 people and displaced millions.