According to the twitter account SAA Reporter, a Syrian journalist working with the Syrian Arab Army has posted images on the 23 November 2015 of alleged Russian T90A tanks being deployed for imminent ground operations.
The tweet also claims that this is the first Russian ground operation though it is unclear at this time if Russian troops or tank operatives will be involved in any imminent operation.
UPDATE 28 November 2015:
According to the opposition RFS (Revolutionary Forces of Syria) Media Office on the 27 November 2015, Russian T90’s and Russian crews have arrived in Syria’s North at the Neirab (al Nayrab) military airport near Aleppo, with a perceived imminent involvement.
They report that allegedly this will be the first time such tanks have been involved in Syria as the Syrian Arab Army does not posses them.