Union State

The Union State, also known as the Union State of Russia and Belarus, is an organization made up of Russia and Belarus that was formed on 8 December 1999. The Union State was originally created to unite both countries. However, both countries still preserve their independence currently. 
The Union State is based on a international treaty between Russia and Belarus made on 2 April 1997. Although its only members are Russia and Belarus, other countries are allowed to join.