Intervening in the autonomous (or semi-autonomous) regions of neighbouring states has been Putin's way of trying to control Russia's "near abroad" from the beginning of his rule. It wasn't a technique he invented as Russia had already been involved militarily in Abkhazia, South Ossetia and Transdniestria in the early 1990s. However, some observers believe back in those days the Kremlin may not have had a coherent policy and was simply responding to events in an ad hoc way. This would explain the somewhat confused handling of the Armenia-Azerbaijan war (1988-1994) in which Russian soldiers fought on both sides.
Putin inherited a situation in which Russian "peacekeepers" were effectively in control of the breakaway Georgian republics of South Ossetia and Abkhazia. In December 2000 Putin used this state of affairs as an instrument for punishing the then Georgian president Edvard Shevardnadze. Putin was angry that Georgia's Pankisi Gorge was being used as a refuge by Chechen fighters during the Second Chechen War which Putin had just started. When Shevardnadze responded that Georgia was incapable of policing the gorge, Putin imposed visa restrictions on Georgians, while issuing Russian passports to Abkhazians and South Ossetians and allowing the free flow of goods between those regions and Russia.
(I may add more detail to this post tomorrow. Putin's actions provoked a series of events which led to Georgia drawing closer to NATO.)