There was a referendum to make Belorusian an official language, one that was to be taught.

There were near riots because it would have intruded on the sanctity of sacred Russian and Russian culture. Just as in Ukraine, rumors were rife--nobody would be allowed to use Russian, you'd be required to be fluent in the language, they were disrespecting Russian and Russia, yada-yada, tak i dalee.

Belorusian is listed as either threatened or endangered in its home territory because of the encroachment of Russian under USSR sponsorship. You needed Russian for all sorts of things, it was required, it was the national medium, but BR was a backwater and widely decried in the mainstream culture as the language of rubes. No PCism, saying all dialects are equal. BR was substandard Russian, whatever the official view, nowhere implemented, may have said.

The "Russian Mir" is strong there, and any deviation from allegiance to Mother Russia and Russian culture will be met with problems, subsidized by the Kremlin. Just look at Ukraine for an example. The guy in charge is bad, but not an idiot. He's at best going to play it like Tito did, but even that's going to require a lot of finesse.