Paul Berman's article at The New Republic is linked below.
Soviet Actions in 1956 and 1968 Shed light on Putin's Approach to Ukraine in 2014
"It is always said of Putin that he is a czar, operating on nineteenth-century principles. Or he is a Russian enigma. And he is not a Kremlin general secretary from Soviet times. Even so, he is a Kremlin general secretary. He has invaded Ukraine on the basis of the same logic that led Nikita Khrushchev to invade Hungary in 1956 and that led Leonid Brezhnev to invade Czechoslovakia in 1968. It is the logic of counterrevolution, and it is not inscrutable."
---Paul Berman, The New Republic