Watch: Nandan Unnikrishnan on the crisis in Ukraine

The crisis in Ukraine is hardly going away – a showdown of two world views that could lift Europe. It echoes the Cold War and revives an idea left over from the Yalta Conference of 1945: the West must respect the Russian sphere of influence in Central and Eastern Europe.

Since coming to power in 2000, Russian President Vladimir Putin has worked relentlessly and systematically to reverse what he thought of as the humiliating breakup of the Soviet Union 30 years ago.