Russian and/or Belarusian

Many customers ask me: is it a must to translate texts into Belarusian (Byelorussian, Belorussian – different spellings are used) when targeting goods and services to the market of Belarus. Well, to be honest, in most cases Russian translation would be enough because about 95% (well, being a big fan of the Belarusian language, I am afraid I am overoptimistic here) of local population speak Russian in their everyday life. So I think that Russian would be better for translating manuals, user guides, instructions, product descriptions, etc. However, if a customer wants his/her product or service to stand out, then I would recommend translating marketing/promotion materials to Belarusian.