"This move was neither surprising, nor disturbing. This is because the Syrian government has not only been informed about the move, but also because the consultations with Syria's government and responsible executives on the ground, the issue was thoroughly considered," Bouthaina Shaaban said as quoted by Al Mayadeen TV channel.
She added that Moscow had announced from the very beginning of its aerial anti-terror campaign that it would not be permanent.
Syria has been mired in civil war since 2011, with government forces fighting numerous opposition factions and radical Islamists. Russia had been conducting an aerial campaign against terrorists in Syria since September 30 at Assad's request.