Despite last week's plan to "de-escalate" the crisis, Ukraine and Russia are now exchanging accusations over Saturday's deadly shootings near the Eastern city of Sloviansk. Russia says Ukraine has failed to crack down on "extremists" as promised last week in Geneva. Ukraine says people were killed in a "crude provocation" staged for Russian TV. Vice President Biden has arrived in Kiev for talks with Ukraine's interim government starting tomorrow, while the Obama White House decides whether to escalate economic sanctions. Would they make any difference in the short term? Does Vladimir Putin want to invade Ukraine, or will continued destabilization suit his purposes? His domestic approval rating is 80% based on nationalism and conservative values. Is that more important than the economy in the short term?