I’ve argued before that if the West wants to stop Russian expansionism, it has to take away the excuse for that expansionism – the oppression of Russian citizens in former colonies like Georgia, Ukraine or the Baltics. This oppression is real, and as long as it exists, as long as the EU isn’t really pro-active in protecting the rights of Russian citizens outside of Russia, then Russia will use this as an excuse for its military sorties.
An interesting historical parallel for this strategy was drawn to my attention today. It turns out that, during the Great Game of the 18th and 19th century, the Russian empire used exactly the same strategy, using the excuse of Russian slaves in central Asia as an excuse to invade the khanates of Khiva and Bukhara and extend the borders of the Russian empire.
The British empire, realizing what Russia was up to, dispatched two secret agents to the khan of Khiva, in what is now Uzbekistan, to persuade him to release all his Russian slaves, which he did, thus removing the excuse for Russian aggression.
You can read about the incident here.