"We have prepared a range of options for our support against Isis [Daesh] including in Syria, which could include troops. It could result in potential clashes with Russians," the outlet quoted the source as saying.
The Russian Aerospace Forces have been carrying out airstrikes against Daesh targets in Syria at the request of the Syrian government since last September.
Ukraine has mobilized tens of thousands of troops since April 2014 to fight militias in two breakaway southeastern regions. It has repeatedly requested assistance from the United States – in terms of equipment, weapons, training and funds.