Even without knowing precisely who fired the missile that destroyed Malaysia Airlines Flight 17, it is safe to say that the blame for the chaos that has overtaken parts of eastern Ukraine, the area from which a missile was launched at an Amsterdam to Kuala Lumpur flight, lies largely at the feet of Russian President Vladimir Putin. What he does now will either begin the process of bringing Russia back into the international fold, or further isolate his country by ramping up a war, attempting to further dismember Ukraine, and destroying relations between Moscow and the West.
Under normal circumstances, the downing of a civilian plane with 298 people aboard would be an opportunity for a leader in Mr. Putin's position to reflect and reconsider. His annexation of Crimea and his support of separatist forces in Ukraine are the root cause of the hostilities there. It has always been within his power to escalate or de-escalate, and the MH17 tragedy has given him the perfect opportunity to begin cooling things down and pushing for peace.
But circumstances are never normal when Mr. Putin is involved. There is no way of predicting whether he will support calls from the United States, Germany and other nations for a ceasefire and an international investigation into the disaster, or hedge, dodge and continue to pretend that the near civil war in parts of eastern Ukraine is the fault of the Ukrainian government and Western interference.
One of the reasons for this unpredictability is the realistic possibility that Mr. Putin has to some extent lost control of the mess he created. There are growing worries that his relentless propaganda has whipped Russian nationalist fervour to such a pitch that those who buy into it can't climb down, and won't allow him to.
Mr. Putin needs to demonstrate to the rest of the world that he is capable of responding appropriately to the international outrage sparked by the MH17 calamity. Evidence suggests that his allies and proxies, who have been targeting Ukrainian aircraft in the country's east, did this. The first step is for him to refrain from trying to cast doubt about who was responsible and to join with other countries in transparently investigating this tragedy. The next step is to back away from the rhetorical and logistical support for eastern Ukraine's rebels.