MOSCOW — Over the years, the Kremlin has reached deep into its bag of tricks to silence Aleksei A. Navalny, the anti-corruption campaigner and opposition leader. He has been repeatedly jailed, harassed by tax auditors and security agents, attacked with green dye and castigated by the state news media as a traitorous lackey of the West.

But this week, Viktor V. Zolotov, the longtime head of President Vladimir V. Putin’s personal security detail until taking over the Russian National Guard, took things one step further, releasing a video in which he essentially challenged Mr. Navalny to a duel.

The video, laced with prison slang and boorish threats, could have come straight out of “Goodfellas,” or maybe a sendup of a gangster movie.

“I simply challenge you to a fight — in the ring, on the tatami, whatever, and I promise to make nice, juicy mincemeat out of you in a few minutes,” said the speaker, Viktor V. Zolotov. “I promise you that before stepping over you and wiping my feet, I will put on a demonstrative show for all the members of the National Guard.”