Maps about Ukraine, ethnic Russians

I want to show you two maps.  This first one from 1918 gives the lie to the historical myth that Nikita Khruschev's return of Crimea to Ukraine was some kind of historical anomaly. It clearly shows that Crimea and parts of Belarus and Russia were all part of the free Ukrainian People's Republic before the Bolsheviks conquered it:

The second map is an infographic from NPR.  It shows you why other Russian satellite states are nervous about Russia's annexation of Crimea on the basis of ethnic kinship:

The greener the country, the more ethnic Russians live there. As the favored ethnicity in the Soviet Union, Russians were workers, soldiers, managers and party bosses all throughout the Soviet Union.  After the fall of the USSR, many of them or their descendants stayed put.

So the pretext that Putin gave in Crimea could be repeated in, say, NATO member Latvia, to "protect" about half a million ethnic Russians there.  Already, as NPR points out, "since the Crimean crisis broke out, Transnistria's local Parliament has asked Moscow to grant the breakaway region [of Moldova] Russian citizenship and admission to the Russian Federation." And parts of Kazakhstan are more Russian than Kazakh.  

So what is to stop Putin continuing in this way?  So far, only Putin himself.  That is precisely what worries the West and Putin's neighbors alike.