One way of insisting on the separate "Moldavian" identity of the new Moldavian SSR was "transliterating" the local Romanian dialect into Cyrillic (in Romania proper, including the part of the historic Moldova, centered around Iasi, that has always been one of the three major constituent parts of Romania) Latin alphabet is used (though, there is, indeed, some medeival precedent for using Cyrillic). Consequently, a new written standard was formed: Moldavian, as distinct from Romanian.
In fact, Romanian was written in Cyrillic until the mid-19th century, although it was a very different Cyrillic from the one ultimately imposed on the Moldavian SSR.
(The story of the "Moldavian language" is also fairly interesting. Soviet linguists in the 1930's tried to craft a standard from the trans-Dniester dialects that were within their borders, which were actually fairly divergent. When Bessarabia came into Soviet possession, though, they were basically forced to give up that project, write standard Romanian in Cyrillic, and pretend it was a different language. See also: all the Central Asian languages, corresponding to previously nonexistent ethnic divisions.)
