High quality global journalism requires investment. Please share this article with others using the link below, do not cut & paste the article. See our Ts&Cs and Copyright Policy for more detail. Email ftsales.support@ft.com to buy additional rights. http://www.ft.com/cms/s/0/b70c027e-eb89-11e5-888e-2eadd5fbc4a4.html#ixzz439YtcGPt

Vladimir Putin’s partial withdrawal of Russia’s air force from Syria has led to speculation he is ready to jettison Bashar al-Assad, the Syrian president who was saved by Russia’s military intervention last September.