(1) Putin craves overland access to the Russian naval base in Tartus, Syria, so he can control the nearby Suez Canal to cut off easy access to Middle East oil making Russia's mafia-owned (a.k.a. Putin's) oil reserves much more valuable, so that ultimately, he can reconstitute the (highly profitable) USSR.
(2) Trump craves building a massive hotel and casino in Moscow.
(3) Putin and Trump have a Russian mafia money-laundering relationship since the 1990's, so they conspire to help each other.
(4) Putin, first, takes control of former-soviet Georgia's highway infrastructure, then second, makes Turkey's Erdoğon and Syria's Assad his dictatorial vassals, then third, Putin ensures Trump wins in 2016, then forth, at the right moment Trump suddenly get us out of the way of Kurdish-held Syria, then Voilà!, Putin can finally have his overland access to Tartus though Russia, Georgia, and Turkey, and into Syria.
(5, coming soon) Trump gets himself impeached out of office asap so Putin can give him his Trump Tower Moscow.
Does Trump have the intellectual capacity to create and execute this plan? Hell no, but Putin does, and he also knows how to manipulate Trump's huge narsiccistic ego into going along with it, democracy be dammed.
This will go down in history as one of the world's greatest political gambits. Wherever they may be, Sun Tzu, Augustus, and Machiavelli are bowing down in humility before Putin.