The al-Nusra Front is at the centre of the accusation
Russia's foreign minister Sergei Lavrov has accused the United States of attempting to aid a jihadist group in Syria.
Speaking to BBC World News he said: "They pledged solemnly to take as a priority an obligation to separate the opposition from Nusra."
"They still, in spite of many repeated promises and commitments... are not able or not willing to do this and we have more and more reasons to believe that from the very beginning the plan was to spare Nusra and to keep it just in case for Plan B or stage two when it would be time to change the regime," he added.
US protecting Syria jihadist group - Russia's Lavrov - BBC News https://t.co/OkCP6NE72i— David Vujanovic (@DavidVujanovic) September 30, 2016
Today marks one year since Assad requested Russian military aid in the conflict.
The Russian claim centres around the jihadist al-Nusra Front who they say the Americans want to keep in the equation in Syria if Assad isn't removed from power.
Lavrov also defended Russian bombing of Aleppo claiming the al-Nusra front are based there and every ceasefire in the area allows the group to resupply itself.
"Humanitarian things are very important and we are doing everything now together with the Syrian government to help the United Nations to get weekly pauses in Aleppo to deliver humanitarian goods. It's the Nusra-controlled people in eastern Aleppo who refuse to do this," he said.
The Russians have been heavily criticised by aid organisations earlier this week for now allowing the necessary supplies to be delivered to the area.