Westerners strain to predict Moscow's next moves in Ukraine, and elsewhere.
President Vladimir Putin may think that Russia can weather Western reactions if he decides to move beyond the occupied part of eastern Ukraine, perhaps seeking to forge a land bridge between Russia and Crimea.
But will he consider economic and political constraints, akin to those that hastened the fall of the USSR after its intervention in Afghanistan?
A Kremlin decision to widen its assault in Ukraine might not be irrational. But would it be imprudent? This question is more complex.