"However, we have noticed no steps to separate opposition and al-Nusra Front," Gen. Valery Gerasimov said.
Earlier in the day, Russia circulated in the UN Security Council a draft statement on the necessity to separate moderate opposition from terrorists in Syria, in the light of the halting the airstrikes by the Russian and Syrian forces in the Aleppo area.
He said that terrorists continue shelling residential districts in the city of Aleppo using rocket launchers and artillery.
The general said Washington has not yet made a single step in battling international terrorism in Syria.
"From the military point of view, terrain and landscape at the Syrian-Iraqi border provide an opportunity for the US-led coalition to prove its commitment to fighting international terrorism (operation in Mosul) in practice. In contrast with Syria, where our American partners have not made a single step in this direction so far," he added.
Syria has been mired in civil war since 2011, with government forces loyal to President Assad fighting numerous opposition groups and terrorist organizations such as Daesh and al-Nusra Front. Since the war's beginning it has claimed lives of thousands of people and displaced millions more. The international community has undertaken steps to end the Syrian conflict and to solve the humanitarian crisis in the Middle Eastern country.
On September 9, Russian Foreign Minister Sergei Lavrov and US Secretary of State John Kerry unveiled a peace plan to address the conflict. The ceasefire deal was later shattered by numerous violations, which resulted in intensified fighting between the Syrian government and militants in Aleppo. The Syrian government has announced an end to the ceasefire regime, while Russia said that the United States failed to fulfill its obligation to separate terrorist groups from moderate opposition.