Country bordering Latvia, Belarus, Poland and Russia. Part of Poland from the Middle Ages until Poland was divided up by Russia and Prussia in the late 1700s. Became independent after World War I; in 1939 after a mutual-assistance treaty with the Soviet Union was signed, a pro-Soviet government came to power and voted to ask to become part of the Soviet Union and the USSR agreed in August 1940. (The US never recognized the annexation.) In 1991, it was one of the first Soviet republics to become independent again.