Putin will strike Donbass
It's not likely that Putin's next surprise move will come until after Russia's presidential election in March. If at that point the transatlantic community appears sufficiently divided, he will look for a way to test NATO.
One option is to foment an ethnic Russian protest in one of the Baltic states. If protesters take control of government buildings, the Kremlin would leverage that toehold to erode consensus around NATO's collective defense protections for the Baltic and Eastern European states. But Putin's more likely move will be further south: If Ukraine makes strides in its economic and political reforms, he could turn up the military heat in Donbass, the pro-Russian region in the eastern part of the country.
Alternatively, he might beef up Russia's basing arrangement with Nicaragua or set up a new base in Venezuela or Cuba, hoping to to pressure Trump to eliminate sanctions and to cave to Russian demands in Ukraine and Syria.
The bottom line: As always, Putin's goal will be to retain power, in part by keeping the United States weakened, divided and out of Russia's sphere of influence in Eastern Europe and Central Asia.