When the chairman and chief executive of Total SA, Christophe de Margerie, was killed this week after his private jet hit a snow-removal truck on takeoff from a Moscow airport, it looked like an accident.

Russian television viewers were treated to a different version. According to a top Russian television channel, a plot by the Central Intelligence Agency couldn’t be ruled out. Mr. de Margerie was, after all, a prominent opponent of U.S. and European Union sanctions on Moscow, and Washington wanted him silenced. This story was relayed not by an outraged nationalist pundit but by a newscaster.

The report illustrates a development that is becoming increasingly evident: Russians and Westerners are talking past each other. It isn’t just that they have different opinions about the same event; it is that they believe in a different set of facts.

It is like “two people in a dark room,” said an American participant at a Valdai Club conference near Sochi this week that brings together Russian officials and academics with Western experts.

Nowhere is this more apparent than over events in Ukraine. To a vast majority of Russians, the ouster of former President Viktor Yanukovych in February was a coup that had the direct support of European politicians and was fomented by Western intelligence agencies. For Westerners, Mr. Yanukovych fled under pressure from a popular movement that sought closer relations with the West.