To understand why Vladimir Putin is willing to take the kinds of risks that produced the destruction of a civilian airliner, and why the US and its allies should see his power play as an effort to alter not just the arc of Ukraine but all of Europe it is necessary to look at the tale of two countries. Poland, integrated into Western economy and grew twice as fast as Ukraine. Many think this contrast scared Mr. Putin particularly when Ukraine, emulating Poland, began to pivot westward earlier this year. To allow the Ukrainian turn to happen would have been the end of any near-term dreams of rebuilding a Russian empire. The goal of re-creating a Russian sphere of influence collided head-on with the spread of a Westernized EU model for Europe seeping toward Russia's doorstep. Mr. Putin faced a historic choice: swim with the tide or try to turn it. He chose the latter.