There was no military occupation of Finland in the 1990s.
A was referring to the Baltic countries, as per the comment from @kibwen above.
Sorry, my bad.
"Do you have Russian soldiers in Finland?"
"Yes, hundreds of thousands"
"Where are they stationed?"
"Along the border, six feet deep".
It was the case during the Soviet occupation and briefly during the transitional period, but otherwise - no, it wasn't. For example, in 1990, Latvia simply restored its 1922 constitution (still in effect today, although with some amendments) which enacted Latvian as the sole official language. This has also been the case with Lithuanian and Estonian constitutions, respectively.