Part of the problem with the Ukainian Civil War, that has been going on since 2014, is that the Russian East of Ukraine - ethnically, culturally, and economical

Part of the problem with the Ukainian Civil War, that has been going on since 2014, is that the Russian East of Ukraine - ethnically, culturally, and economically Russian was viewed as being targeted by the Pro-Western Ukrainian from the West of the country. Putin styles himself as the "Defender of Ethnic Russians". Whether that is an excuse or a serious reason is probably a political question. Given that, and the NATO encroachment, I'd think there would be an excellent reason for Putin to want Transnistria - pushing the borders back that far gives him buffer zones that includes Mountain ranges and help shore up his defenses if he captures all of Ukraine. Because Transnistria is mountainous, it provides a barrier for invading forces, and a number of attractive choke points.