Less than a month after the United Kingdom’s 1939 declaration of war against Nazi Germany, Winston Churchill famously described Russia’s actions as "a riddle, wrapped in a mystery, inside an enigma." Churchill’s quote likely still rings true today in how Western leaders view their Russian counterparts -- especially regarding Moscow’s aggression in Ukraine. But it is probably an even more accurate description of the trillion-dollar question North American and European governments are facing if Russia invades Ukraine -- that is, how to sanction the Russian economy in a way that maximizes pressure while minimizing blowback. ...