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, a pact with Russia broadened residency criteria to include immigrants from Russia who arrived in Lithuania between 1989 and when the treaty was ratified. Subsequent applicants needed to fulfill naturalization requirements, which included language tests in Lithuanian.