Interpreting the Russian Withdrawal from Syria - Syria in Crisis - Carnegie Endowment for International Peace
▻http://carnegieendowment.org/syriaincrisis/?fa=63042
Putin may be telling the truth. The Russian intervention has achieved quite a lot. It has undercut the Syrian opposition, stabilized Assad’s government, and produced a peace process on more favorable terms for Assad than was previously possible. Perhaps Putin was always planning for an intervention of limited duration and kept Assad informed about this. With a truce in place, now is a good time to start scaling it down.
Meanwhile, other forms of support to the Syrian government are likely to continue and, if the peace process collapses, Putin could easily reverse his decision. Remember, the Hmeymim and Tartus bases will remain operational, which leaves Russia with all the infrastructure it needs to resume airstrikes on short notice.
Putin may be bluffing. The Russian government is not above a bit of wartime subterfuge and Putin saying something is not the same as Moscow actually doing it. The Kremlin has very consistently lied about its troop presence in eastern Ukraine and about what insurgent factions are being targeted in Syria. It is possible that the Russian president is simply telling his enemies what they want to hear, in order to mollify critics in the White House and gain time, without any intention of stopping the attacks.