1. Mr. Putin has a lot to hide. Sure, he could have fessed up about the MH17 shoot-down (as the U.S. did after shooting down an Iranian passenger plane in 1988—eventually paying compensation, expressing regret, and moving on). But doing so would have made it harder to keep lying about the Russian military presence in eastern Ukraine—and Mr. Putin finds it harder to admit the truth about that. His lies are inter-linked.
3. Mr. Putin recycles lies that his own people tell him. Anyone who has dealt with senior Russian officials, up to and including the Russian president, has heard them make claims, usually about the secret workings of U.S. policy, that are so bizarre and preposterous you would think no normal person could believe them. This problem—unquestioning acceptance of information circulated by intelligence services—exists everywhere, but it seems especially acute in the Russian system and makes defaming the U.S. all too easy.
4. Mr. Putin’s position depends on keeping the truth covered up. There’s no evidence, in my view, that he was directly involved in Russia’s most shocking murders of recent years, from the journalist Anna Politkovskaya in 2006 to opposition leader Boris Nemtsov in 2015. But Mr. Putin guards the system that covers up these crimes—a system so corrupt that it would be very hard to decide where to let the truth emerge without having everything unravel. Mr. Putin’s solution: Cover it all up.
These explanations paint an unattractive picture of Vladimir Putin as a political leader, but to my mind a final reason for his systematic lying is the most damning of all: Mr. Putin doesn’t see its costs.