WARSAW — There may be no other misfortune that fires up people’s imaginations the way a plane crash can. It must be the blatant role of fate in such a situation: The tiniest oversight may bring an unavoidable death to a randomly gathered group of people.

Before last week's crash of the Malaysian Boeing, the conflict in Ukraine was to the majority of the globe a regional issue that few cared about. Today, everybody is concerned and wondering where the separatists obtained the weapon: Was it from the Ukrainian military base taken over in the region a few weeks ago, or from Russia, whose Special Forces have been smuggling arms across the border into Ukraine?

The answer is vital to identifying the main culprit of the tragedy. If a monkey has a razor, the one responsible for any fatal outcome is whoever who put it in its hands.

All signs point to the pro-Russian separatists playing the role of the monkey in this tragic story. Who else could be so hasty, ignorant and amateur as to not distinguish a military plane from a civilian one? Some journalists hint that the blame lies with the Russian regular army stationed on the Ukrainian border, but this version seems highly improbable.

In this most likely scenario, several should share responsibility for such a catastrophe. It is most astonishing that the majority of airlines have continued to fly over the territory of the self-proclaimed Donetsk People’s Republic where a regular war has been going on. Just a few days before the crash of the MH17 flight, a Ukrainian military plane was shot down from a height of 6,000 meters. So it should not come as a surprise that the separatists already had a weapon capable of reaching a target at great heights.

These unchanged flight paths are further proof that the world has dramatically underestimated the Ukrainian conflict.

But looking ahead, this catastrophe could be a cold shower for Vladimir Putin’s hot temper, even if there is little hope that he will suffer from pangs of conscience. The second war in Chechnya (1999–2009) cost the lives of tens of thousands civilians — but it did not make the Russian president stop the offensive.

The more probable outcome is that the tragedy will spark a turn in the attitude of Western leaders. Until recently, the most important of them have continued doing business with Putin despite the scandalous Russian activity in Ukraine. The only exception from the rule is Barack Obama, who announced new sanctions against Russia a day before the plane crashed.

Now, European leaders are under enormous pressure: It will be difficult to behave as if nothing happened when dealing with a man who probably contributed to the death of 298 Europeans.

If European leaders follow world public opinion, there might be a chance for a quick end to the conflict in Ukraine. As its greatest economic partner, Europe has the power to do much harm to Russia. Naturally, it would have to run the risk of harming itself, because sanctions are a double-edged sword. But perhaps this is the moment to take that risk, keeping in mind the memory, and fate, of 298 people killed on their way to Kuala Lumpur.