Earlier quoted context omitted.
Well, Lithuania was occupied and a part of Soviet sphere at the time. Although it's always nice when other parts of USSR get individual mentioning rather than just Soviet=Russian.
A sheer number of Lithuanians participated in The Revolution. Who invaded whom is questionable. Especially in the light of Lithuanuan Duchy expansion some 200 years before.
Lithuania territory at either time was smaller than original GDL territory "some 200 years ago" before the expansions. It was core GDL territory since first internationally recognised state in that area was formed in 13th century and stayed so till the Partitions in late 18th century.
Also, there was that simple act of sending ultimatum to replace government to a specific one, holding staged elections and then having that government "ask to join" USSR. All under overwhelming USSR army presence. Pretty much textbook occupation if you ask me...