Transnistria, also known as Pridnestrovian Moldavian Republic, is a breakaway republic within the ex-Soviet state of Moldova. It is an autonomous territory, with its own government, parliament, military, police, postal system and its own currency, constitution, flag, a national anthem, etc.
Landlocked and very small Transnistria is located between the Dniester River in Moldova and Ukraine. The region had been part of the Russian Empire since 1792. The War of Transnistria triggered the PMR's declaration of independence in 1990. Russian troops have remained in the region as a peacekeeping force since 1992, "protecting" the 300,000 and 400,000 Transnistrians (which are nothing more than ethnic Moldovans, ethnic Russians and Ukrainians.)
Russia has no problem supporting geographical regions outside of Russia that declare their independence, especially if those autonomous regions are within ex-Soviet states.
Transnistria will be one of the next regions rescued by the gallant Russians. South Ossetia and Abkhazia were just the first in a series.