MOSCOW—As Russian riot police violently suppressed pro-democracy demonstrations across Moscow, detaining around 1,000 people, some pro-Kremlin state news channels featured a different top news item: a city-sponsored barbecue festival on the leafy banks of the Moscow River.

Russian state media’s studious dismissal of the nascent protest movement has helped the Kremlin keep its attempts to quash the protests off-screen, avoiding the images of police beating young protesters that could feed into broader anger across the country.

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