Temporary capital of Lithuania during the invasion of Poland, to Lithuania according to the Soviet–Lithuanian Mutual Assistance Treaty. Since then Vilnius has been the capital of the Lithuanian SSR and then independent Lithuania. Lithuania refused to have diplomatic relations between Poland and Lithuania until the ultimatum of 1938. Railroad traffic, telegraph lines or even mail could not cross the Polish–Lithuanian border. Lithuania continued to declare Vilnius as its capital in all official documents, including the constitution. Since the city was controlled by Poland, all Lithuanian authorities were transferred to the city of Kaunas, which became the seat of the government. To reconcile reality with
Act of the Re-Establishment of the State of Lithuania Act of the Re-Establishment of the State of Lithuania The Act of the Re-Establishment of the State of Lithuania or Act of March 11 () was an independence declaration by the Lithuanian Soviet Socialist Republic adopted on March 11, 1990, signed by all members of the Supreme Council of the Republic of Lithuania led by Sąjūdis. The act emphasized restoration and legal continuity of the interwar-period Lithuania, which was occupied by the USSR and lost independence in June 1940. It was the first time that a occupied state declared independence from the dissolving Soviet Union. After the partitions of the