Defense agreements between Syria and Russia will likely have seen Syrian troops going to Russia for training. It's what happens globally between partners in defense. Take the three Adams Class Destroyers the Australians bought....the crews went to the US prior to launch and did familiarisation on American active Adams class destroyers then sailed the new vessels back to Oz....armed and supplied themselves and went straight into battle in Vietnam as forward air defense and Naval Gunfire support. All ships made a good account of themselves and H.M.A.S Hobart recieved highest Battle honours and fired more lead into Vietnam than the entire Aussie Fleet fired anywhere during WW2. Training is a low hurdle.
U.S., allies conduct 20 air strikes in Syria and Iraq against ISIS, says U.S. military (Reuters)