Last year, noted President Obama in his recent State of the Union address, his critics were saying Russian President Vladimir Putin's aggressive moves into neighboring Ukraine were "a masterful display of strategy and strength."But now, he added, after Western countries levelled stiff economic sanctions against Moscow, "Russia is isolated, with its economy in tatters."He's right about the economic impact of sanctions -- helped along by plunging oil prices. Days after Obama spoke, bond-rating agency Standard and Poor's downgraded Russia's credit rank to "junk" status. The ruble has lost half of its value against the dollar, and investors pulled $152 billion out of the country last year.The problem is that Putin seems undeterred by these economic penalties.