It’s been more than 20 years since al-Qaida’s Osama bin Laden boasted of his success in bringing down New York’s twin towers — and there are still millions of people who prefer to believe that the CIA or Jews were responsible.

So it’s no surprise that conspiracy theories are multiplying just days after terrorists murdered at least 143 people at a Moscow concert hall.

What’s different this time is the role of the state in spreading this nonsense, because the reality is so much more banal and — from the point of view of Russia’s security forces — so much harder to explain: A spectacular level of incompetence married, as I’ve written previously, to a destructive paranoia at the pinnacle of the Russian state.