A 1991 treaty with Russia extended the definition of residency to those who had immigrated to Lithuania from Russia between 1989 and the ratification of the treaty. Subsequent applicants for citizenship were required to meet a set of naturalization standards, including Lithuanian language testing.
In 1991, an agreement with Russia broadened residency eligibility to include immigrants from Russia who arrived in Lithuania between 1989 and the ratification of the treaty. New citizens were then required to meet naturalization requirements, which included a Lithuanian language test.